[0.85] Add Fast Refresh performance marker and unstable_fastRefreshComplete CDP event

[motiz88]

Target Branch

0.85-stable

Link to commit or PR to be picked

facebook/react-native#56639

Description

Cherry-pick of 2 commits from main adding a Fast Refresh performance timeline marker (facebook/react-native#56176) and an experimental unstable_fastRefreshComplete CDP event (facebook/react-native#56273), plus a Metro dependency bump to ^0.84.3 (which adds changeId to HMR update-done messages, required for event deduplication).

Previously backported to 0.83-stable in facebook/react-native#56399.

cc @huntie

[github-actions]

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These are the criteria we follow when accepting or rejecting a code change into a React Native release branch (source).

If your Pick Request does not satisfy the criteria below, please close it as it will not be considered.

✅ Which Pick Requests we accept

1. ✅ Fixes for regressions to core APIs. Examples:
   • A core component is behaving differently between versions 0.X and 0.X-1
   • The TurboModule.getEnforcing function is throwing an unexpected assertion error.
2. ✅ Fixes to bugs in core React Native. Examples:
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