Improve Gutenberg block processors performance to avoid long delay when saving a post

[fluiddot]

Fixes wordpress-mobile/gutenberg-mobile#6696.

Note

Uses the changes from #22886.

[Add Benchmark]

To test

Follow the testing instructions to cover the functionality related to the processors for each block:

• Gallery block:

  • Close/Re-open post with an ongoing image upload
  • Close post with an ongoing image upload

• Image Block:

  • Close/Re-open post with an ongoing image upload
  • Close post with an ongoing image upload

• File Block:

  • Close the post with an ongoing file upload
  • Close/Re-open post with an ongoing file upload

• Cover Block:

  • Close/Re-open post with an ongoing image upload
  • Close post with an ongoing image upload

Regression Notes

1. Potential unintended areas of impact
   The block processors are only used when saving a post. No other area should be impacted.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Manually tested saving a post with different blocks. Additionally, each processor has its own unit test that has been verified.

3. What automated tests I added (or what prevented me from doing so)
   Some unit tests have been added to cover the content parsing.

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Testing checklist:

• WordPress.com sites and self-hosted Jetpack sites.
• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• VoiceOver.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• iPhone and iPad.
• Multi-tasking: Split view and Slide over. (iPad)

[dangermattic]

	1 Warning
⚠️	This PR is larger than 500 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.

	1 Message
📖	This PR is still a Draft: some checks will be skipped.

Generated by 🚫 Danger

[wpmobilebot]

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

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr22845-5547592
	Version	24.5
	Bundle ID	org.wordpress.alpha
	Commit	5547592
	App Center Build	WPiOS - One-Offs #9232

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[wpmobilebot]

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

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr22845-5547592
	Version	24.5
	Bundle ID	com.jetpack.alpha
	Commit	5547592
	App Center Build	jetpack-installable-builds #8277

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.

[fluiddot]

I'm considering splitting this PR into smaller PRs, one for each block processor.

[fluiddot]

I'm considering splitting this PR into smaller PRs, one for each block processor.

Closing in favor of new PRs.