[ECO-4904] Add Unified Test Suite CI action

[VeskeR]

Context

Resolves ECO-4904.
See Unified Test Suite repo for Chat at: https://github.com/ably-labs/unified-test-suite-chat.

Description

• Describe the changes introduced in this PR
• Provide relevant context or considerations for reviewers.
  • Such as why the changes are necessary,
    or how they affect the system.

Checklist

• QA'd by the author.
• Unit tests created (if applicable).
• Integration tests created (if applicable).
• Follow coding style guidelines found here.
• TypeDoc updated (if applicable).
• (Optional) Update documentation for new features.
• Browser tests created (if applicable).
• In repo demo app updated (if applicable).

Testing Instructions (Optional)

• See result of the "Unified Test Suite" action on github

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🟢	Lines	94.18% (🎯 92%)	2853 / 3029
🟢	Statements	94.18% (🎯 92%)	2853 / 3029
🟢	Functions	93.39% (🎯 93%)	212 / 227
🟢	Branches	94.25% (🎯 93%)	771 / 818

File Coverage

No changed files found.

Generated in workflow #1552 for commit 16e355d by the Vitest Coverage Report Action

[ttypic]

LGTM