Issue/cmm 278 react response thread exception

[nbradbury]

Fixes #CMM-278

This PR makes sure we call onSuccess and onError in ReactNativeRequestHandler.handleResponse on the main thread.

We were unable to reproduce the problem, but the crash is a CalledFromWrongThreadException so calling from the main thread seems like the right solution (as suggested by Sentry's "Seer" AI). Note this is our leading crash right now, with 334 users and 1.1K events.

To test, I recommend simply setting a breakpoint on the two changes and verify it all works as expected.

[dangermattic]

	1 Warning
⚠️	PR is not assigned to a milestone.

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[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21802-2292055
	Commit	2292055
	Direct Download	wordpress-prototype-build-pr21802-2292055.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr21802-2292055
	Commit	2292055
	Direct Download	jetpack-prototype-build-pr21802-2292055.apk

Note: Google Login is not supported on these builds.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 39.32%. Comparing base (64f0cea) to head (2292055).
Report is 1 commits behind head on trunk.

Files with missing lines	Patch %	Lines
.../ui/posts/reactnative/ReactNativeRequestHandler.kt	0.00%	8 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            trunk   #21802   +/-   ##
=======================================
  Coverage   39.32%   39.32%           
=======================================
  Files        2125     2125           
  Lines       99871    99871           
  Branches    15385    15385           
=======================================
  Hits        39277    39277           
  Misses      57114    57114           
  Partials     3480     3480           

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[dcalhoun]

Given we do not have reproduction steps, it is difficult to be confident this will address the crash. That said, given the crash reports, the proposed changes make sense.

I smoked tested both Gutenberg Mobile and GutenbergKit—adding various block types, uploading media, etc. I also tested offline editing. I did not encounter any issues. 🚀