Add fix to ensure Super List is installable from the Block Library search

[aurooba]

Currently block.json is not loaded dynamically when people install a block from the block library search. This means if there are items missing in index.js, it causes all sorts of issues. This has been reported and documented in the following issues in the Gutenberg repo:

• Installing Blocks from the Block Library doesn't always work 5.9 WordPress/gutenberg#38588
• block.json not loaded on block plugin dynamic load WordPress/gutenberg#38494
• Block Directory: Activation of a block with no title property will result in an error WordPress/gutenberg#38245

In light of this information, this PR pulls all the metadata from block.json files and pops it into index.js