On-device tests for #2335

[avtolstoy]

Problem

See #2335

Solution

This PR:

1. Adds CLOUD_04_socket_errors_do_not_cause_a_full_handshake test to wiring/no_fixture test suite to simulate socket errors by closing the cloud socket and validating that cloud connection is re-established without performing a full handshake
2. Adds CLOUD_05_loss_of_cellular_network_connectivity_does_not_cause_full_handshake test to wiring/no_fixture test suite to simulate socket errors due to low signal/cellular network conditions by causing a cellular network disconnect and checking that cloud connection is re-established without performing a full handshake
3. To facilitate above tests two new cloud_status system event types were added: cloud_status_session_resume and cloud_status_handshake.
4. To facilitate CLOUD_04_socket_errors_do_not_cause_a_full_handshake system_internal() was extended to provide cloud socket id.

This PR also fixes a bug in NETWORK_01_LargePacketsDontCauseIssues_ResolveMtu.

Steps to Test

Run CLOUD_* tests in wiring/no_fixture suite.

Example App

N/A

References

• Do not reset the session on socket errors #2335
• [ch82443]

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[sergeuz]

Note that unsubscribing from system events is not implemented 😅

[avtolstoy]

Added some final fixes for R410-based devices and re-ran on all devices: ✔️ passed