Gutenberg: Change primary action to Attempt Block Recovery

[gwwar]

Breaking out an actionable piece of #37230

This is a two parter:

• Open a try PR in Gutenberg that does the same thing. We're not sure if the community is interested in this, but we can see!
• Create a wpcom customization that makes Attempt Block Recovery the primary action Edit: (Likely no longer needed for now with Gutenberg: autofix block validation issues on editor load #38397 landed)

Context

When a block parses HTML markup, it also tries to validate the data by re-serializing and comparing the result. Unfortunately blocks currently compare with an exact string match. Even a small whitespace for change for completely equivalent markup/styling, is enough to cause the following scary error:

Clicking on the primary action usually isn't what the user wants. It converts the previously nice to understand block into a plain HTML block:

The best action is usually "Attempt Block Recovery" or "Convert to Blocks"

Traditionally WP allows manipulation of content from a variety of filters/customizations, so this is a very easy case to fall into.

[jeraldjuice]

Closing this for now, based on ongoing discussion in WordPress/gutenberg#19188

[gwwar]

Please keep this one, as my try PR is very unlikely to make it in ;)

[github-actions]

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