Block inserter blinks

[htmgarcia]

WordPress 6.2 RC-4 Gutenberg 15.1 Only when Block permissions is enabled.

[htmgarcia]

Temporary solution. We'll complement based on feedback from https://github.com/WordPress/gutenberg/issues/15993 and https://github.com/WordPress/gutenberg/issues/49409

[htmgarcia]

While the original issue was fixed with first fix, this second round of fixes is still limited for the general purposes of saving new blocks and allowing its use when not saved in database.

• After any other plugin has been activated, the new blocks if any are saved in database, except the ones that uses block.json metadata
• Block types that uses block.json that are still not saved in database, are available in post edit (one time) with a new way to set allowedBlockTypes setting. The second load of post edit, the block(s) are already in database.