Add support for Reusable & Classic blocks

[wpengine]

Add support for Reusable & Classic blocks

[theodesp]

Hey @AndrewIontton93 thanks for the feedback.
Looking at the block.json for the CoreFreeform it looks like we need to handle an edge case here to retrieve the innerHTML for the block content.

Upon looking at the parsed CoreFreeform it looks like that Gutenberg does not save the blockName which is problematic:

{
  "data": {},
  "blockName": null,
  "attrs": [],
  "innerBlocks": [],
  "innerHTML": "\n\n<p>Example Freeform content</p>",
  "innerContent": [
    "\n\n<p>Example Freeform content</p>"
  ]
}

This is problematic since we are filtering the blocks that have no name even when they may have html content.

In that case I will open a ticket. to provide a custom handler for blocks that have no name to fallback to CoreFreeform as long as they are not empty.

As for the reusable blocks this would be a different ticket altogether.

I will let you know when we tackle the above issue with CoreFreeform since there is no alternative option for now.

[theodesp]

@AndrewIontton93 we will be providing support for Classic blocks in this sprint.

[theodesp]

#59