Gutenberg/1.14.0

[marecar3]

This PR updates the gutenberg-mobile reference to point to the latest release, v1.14.0.

The reference is currently pointing to the release/1.14.0 branch on https://github.com/wordpress-mobile/gutenberg-mobile. Relevant PR: wordpress-mobile/gutenberg-mobile#1392.

To test:
The block editor should work as normal.

Update release notes:

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

[mchowning]

Smoke tested this and everything appears to be working. My only concern is whether we are missing the release notes for @SergioEstevao 's link handling fixes. I think we need those. WDYT?

[etoledom]

I've found some known issues on this release. Not sure if we want to ship these:

• Header level toolbar buttons won't change properly its icon color when it's active: Heading block Hx (level) buttons won't change icon color when active. gutenberg-mobile#1398
• H5 and H6 button levels are not working properly on Header block, when the block was just created: Heading block: H5-H6 not always working properly gutenberg-mobile#1399

Also this one, but It's already on production (not a regression):

• DarkMode placeholder on list block is out of place: [iOS] List block: Bullet overlaps placeholder in dark mode gutenberg-mobile#1391

[etoledom]

I noticed that the fix applied on WordPress/gutenberg#17710 for this issue: wordpress-mobile/gutenberg-mobile#1399 is not working.

Did an investigation and sent a PR to fix it: WordPress/gutenberg#17763

cc @marecar3 @SergioEstevao

[etoledom]

With the last update 5655d94, all the current issues were solved 🎉

Thank you everyone! LGTM