[Gutenberg][Embed block] Include Jetpack embed variants

[fluiddot]

• Gutenberg Mobile PR: [Embed block] Include Jetpack embed variants gutenberg-mobile#4008
• Gutenberg PR: [RNMobile][Embed block] Include extra embed variants WordPress/gutenberg#35155
• WPAndroid PR: [Gutenberg][Embed block] Include Jetpack embed variants WordPress-Android#15378
• Jetpack PR: [RNMobile] Embed block: Add index native version to control the available variations Automattic/jetpack#21167

To test:
Follow testing instructions from wordpress-mobile/gutenberg-mobile#4008.

NOTE: Only the Instagram embed variant shows up in the block picker when using the installable build, the rest can be tested via the slash inserter.

Regression Notes

1. Potential unintended areas of impact
   The only expected area of impact is the editor and its initialization process.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Smoke testing the editor, specifically the following parts:

• Editor initialization
• Block picker
• Slash inserter
• Jetpack blocks

3. What automated tests I added (or what prevented me from doing so)
   N/A

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.

[peril-wordpress-mobile]

You can trigger an installable build for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[jd-alexander]

Thanks for these changes @fluiddot I have verified that the respective embed blocks work as expected via wordpress-mobile/gutenberg-mobile#4008 (review)