[cli] Improve span merging in the coverage tool

[Rqnsom]

Description

• Improve merging spans in the coverage tool
  • The old solution failed to merge neighbouring spans: e.g. [3, 5] and [5, 7] into [3, 7]
• Also, make the merge_spans function public so it could be used by the move-mutation-test tool that also parses the coverage output file.

How Has This Been Tested?

• A new unit test has been written.
• cargo clippy hasn't introduced any new warnings for the new change.
• I ran the aptos move coverage tool locally to ensure it still works as expected.

Key Areas to Review

This should have no visible impact on current aptos move coverage tool. The old limitation was not an issue, since displaying covered lines with always worked fine although spans were not merged "perfectly". This improvement is much more important for the usage in the move-mutation-test tool.

Type of Change

• New feature
• Bug fix
• Breaking change
• Performance improvement
• Refactoring
• Dependency update
• Documentation update
• Tests

Which Components or Systems Does This Change Impact?

• Validator Node
• Full Node (API, Indexer, etc.)
• Move/Aptos Virtual Machine
• Aptos Framework
• Aptos CLI/SDK
• Developer Infrastructure
• Move Compiler
• Other (specify)

Checklist

• I have read and followed the CONTRIBUTING doc
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I identified and added all stakeholders and component owners affected by this change as reviewers
• I tested both happy and unhappy path of the functionality
• I have made corresponding changes to the documentation

[trunk-io]

⏱️ 15m total CI duration on this PR

Job	Cumulative Duration	Recent Runs
rust-move-tests	9m	🟩
check-dynamic-deps	2m	🟩
rust-cargo-deny	2m	🟩
general-lints	27s	🟩
permission-check	23s	🟥 🟥 🟩 🟩 🟥 (+2 more)
permission-check	21s	🟥 🟥 🟩 🟩 🟥 (+2 more)
semgrep/ci	20s	🟩
file_change_determinator	10s	🟩

_{settings ⋅ feedback ⋅ docs ⋅ learn more about trunk.io}

[vineethk]

Minor comments, will approve once fixed.

[vineethk]

Thanks for addressing the comments!

[brmataptos]

Looks ok, though the coverage problems are deeper than this.

[github-actions]

✅ Forge suite realistic_env_max_load success on d7abff86c308f32ecbdbd7a23b94d4f831e557fd

two traffics test: inner traffic : committed: 14298.10 txn/s, latency: 2780.93 ms, (p50: 2700 ms, p70: 2700, p90: 3000 ms, p99: 4500 ms), latency samples: 5436500
two traffics test : committed: 100.08 txn/s, latency: 1457.15 ms, (p50: 1400 ms, p70: 1500, p90: 1500 ms, p99: 2400 ms), latency samples: 1720
Latency breakdown for phase 0: ["MempoolToBlockCreation: max: 2.048, avg: 1.576", "ConsensusProposalToOrdered: max: 0.319, avg: 0.293", "ConsensusOrderedToCommit: max: 0.387, avg: 0.374", "ConsensusProposalToCommit: max: 0.679, avg: 0.667"]
Max non-epoch-change gap was: 1 rounds at version 5009803 (avg 0.00) [limit 4], 1.80s no progress at version 5009803 (avg 0.20s) [limit 15].
Max epoch-change gap was: 0 rounds at version 0 (avg 0.00) [limit 4], 8.59s no progress at version 1908718 (avg 8.30s) [limit 15].
Test Ok

• Grafana dashboard
• Humio Logs
• Axiom Logs
• Validator CPU Profile
• Fullnode CPU Profile
• Test runner output
• Test run is land-blocking

[github-actions]

✅ Forge suite framework_upgrade success on 2bb2d43037a93d883729869d65c7c6c75b028fa1 ==> d7abff86c308f32ecbdbd7a23b94d4f831e557fd

Compatibility test results for 2bb2d43037a93d883729869d65c7c6c75b028fa1 ==> d7abff86c308f32ecbdbd7a23b94d4f831e557fd (PR)
Upgrade the nodes to version: d7abff86c308f32ecbdbd7a23b94d4f831e557fd
framework_upgrade::framework-upgrade::full-framework-upgrade : committed: 1344.46 txn/s, submitted: 1347.59 txn/s, failed submission: 3.13 txn/s, expired: 3.13 txn/s, latency: 2266.30 ms, (p50: 2100 ms, p70: 2400, p90: 3600 ms, p99: 5200 ms), latency samples: 120140
framework_upgrade::framework-upgrade::full-framework-upgrade : committed: 1345.36 txn/s, submitted: 1347.99 txn/s, failed submission: 2.63 txn/s, expired: 2.63 txn/s, latency: 2184.70 ms, (p50: 1800 ms, p70: 2300, p90: 3600 ms, p99: 5800 ms), latency samples: 122840
5. check swarm health
Compatibility test for 2bb2d43037a93d883729869d65c7c6c75b028fa1 ==> d7abff86c308f32ecbdbd7a23b94d4f831e557fd passed
Upgrade the remaining nodes to version: d7abff86c308f32ecbdbd7a23b94d4f831e557fd
framework_upgrade::framework-upgrade::full-framework-upgrade : committed: 1374.06 txn/s, submitted: 1377.00 txn/s, failed submission: 2.95 txn/s, expired: 2.95 txn/s, latency: 2445.43 ms, (p50: 2100 ms, p70: 2400, p90: 4100 ms, p99: 5700 ms), latency samples: 121200
Test Ok

• Grafana dashboard
• Humio Logs
• Axiom Logs
• Validator CPU Profile
• Fullnode CPU Profile
• Test runner output
• Test run is land-blocking

[github-actions]

✅ Forge suite compat success on 2bb2d43037a93d883729869d65c7c6c75b028fa1 ==> d7abff86c308f32ecbdbd7a23b94d4f831e557fd

Compatibility test results for 2bb2d43037a93d883729869d65c7c6c75b028fa1 ==> d7abff86c308f32ecbdbd7a23b94d4f831e557fd (PR)
1. Check liveness of validators at old version: 2bb2d43037a93d883729869d65c7c6c75b028fa1
compatibility::simple-validator-upgrade::liveness-check : committed: 14434.85 txn/s, latency: 2398.03 ms, (p50: 2000 ms, p70: 2100, p90: 3000 ms, p99: 8400 ms), latency samples: 542880
2. Upgrading first Validator to new version: d7abff86c308f32ecbdbd7a23b94d4f831e557fd
compatibility::simple-validator-upgrade::single-validator-upgrading : committed: 6850.84 txn/s, latency: 4119.22 ms, (p50: 4600 ms, p70: 4700, p90: 5000 ms, p99: 5600 ms), latency samples: 138200
compatibility::simple-validator-upgrade::single-validator-upgrade : committed: 7252.33 txn/s, latency: 4443.99 ms, (p50: 4600 ms, p70: 4800, p90: 6300 ms, p99: 6600 ms), latency samples: 242340
3. Upgrading rest of first batch to new version: d7abff86c308f32ecbdbd7a23b94d4f831e557fd
compatibility::simple-validator-upgrade::half-validator-upgrading : committed: 7652.22 txn/s, latency: 3752.58 ms, (p50: 4200 ms, p70: 4400, p90: 4400 ms, p99: 4600 ms), latency samples: 143200
compatibility::simple-validator-upgrade::half-validator-upgrade : committed: 7742.33 txn/s, latency: 4160.17 ms, (p50: 4400 ms, p70: 4500, p90: 5600 ms, p99: 6200 ms), latency samples: 257460
4. upgrading second batch to new version: d7abff86c308f32ecbdbd7a23b94d4f831e557fd
compatibility::simple-validator-upgrade::rest-validator-upgrading : committed: 11775.65 txn/s, latency: 2325.65 ms, (p50: 2300 ms, p70: 2700, p90: 3200 ms, p99: 3400 ms), latency samples: 207800
compatibility::simple-validator-upgrade::rest-validator-upgrade : committed: 10336.22 txn/s, latency: 2975.31 ms, (p50: 2300 ms, p70: 3100, p90: 6100 ms, p99: 8100 ms), latency samples: 336560
5. check swarm health
Compatibility test for 2bb2d43037a93d883729869d65c7c6c75b028fa1 ==> d7abff86c308f32ecbdbd7a23b94d4f831e557fd passed
Test Ok

• Grafana dashboard
• Humio Logs
• Axiom Logs
• Validator CPU Profile
• Fullnode CPU Profile
• Test runner output
• Test run is land-blocking