feat(benchmark): support comparing benchmark result

[hi-ogawa]

Description

• Closes Add an API to compare benchmark results #5297

Starting a PR so that we can discuss the design with a proof of concept.

Example

# save current run as bench.json
$ pnpm -C test/benchmark bench --outputFile bench.json
... output is same as before ...

# compare against bench.json
$ pnpm -C test/benchmark bench --compare bench.json

TBD

• what to name the flag? --compare, --baseline? --save-compare?
  • decision: --compare and --output-json
• the feature lives completely in default reporter. json reporter is not used or changed at all, so just keep it as is?
  • decision: remove json reporter
• tweak text/style?
• non-tty output?

TODO

• integrate to current default tty reporter output
• cli flags
• test
  • I couldn't find a way to assert tty output with CI=true. For now, the test is enabled only on local.
• doc

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. If the feature is substantial or introduces breaking changes without a discussion, PR might be closed.
• Ideally, include a test that fails without this PR but passes with it.
• Please, don't make changes to pnpm-lock.yaml unless you introduce a new test example.

Tests

• Run the tests with pnpm test:ci.

Documentation

• If you introduce new functionality, document it. You can run documentation with pnpm run docs command.

Changesets

• Changes in changelog are generated from PR name. Please, make sure that it explains your changes in an understandable manner. Please, prefix changeset messages with feat:, fix:, perf:, docs:, or chore:.

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[sheremet-va]

what to name the flag? --compare, --baseline?

I like --compare

the feature lives completely in default reporter. json reporter is not used or changed at all, so just keep it as is?

Yeah, I don't think we need to update the json output since we get the data for compare from json? 🤔