Allow previewing InnerBlocks in the block editor

[kienstra]

Fixes #96 and GF-3302

Changes

• Allow previewing InnerBlocks in the block editor, where there was no preview before. This is an often-mentioned bug.
• Remove the notice that you can't preview InnerBlocks

Testing Instructions

1. composer i && npm i && npm run dev
2. /wp-admin > Custom Blocks > Add New
3. Create a new block
4. Add a new field
5. Give it a 'Field Type' of 'Inner Blocks':
6. Click 'Template Editor'
7. Enter {{new-field}}:
8. Click 'Publish'
9. Create a new post
10. Add the block you just created:
11. Add some blocks to Inner Blocks:
12. Click away from the block so the preview displays:
13. Expected: The preview includes the blocks you added to Inner Blocks:

[kienstra]

<ServerSideRender /> has no native way to pass it the InnerBlocks HTML.

So it used to not render the InnerBlocks.

As a workaround, we pass the InnerBlocks to the urlQueryArgs prop.

Then, we look for that query arg in InnerBlocks::validate() with filter_input().

[kienstra]

Hi @mikemcalister,
Just added testing instructions here, like we talked about.

[kienstra]

There will still be escaping in block_field() if they call that.

[mikemcalister]

Looks great Ryan! Thanks for the detailed testing instructions. 👏

[kienstra]

@mikemcalister, thanks a lot for reviewing and approving this!

[kienstra]

Here's a .zip of this branch, in case you'd like to test it: genesis-custom-blocks.1.4.1.zip