All Menus: Add experimental "All Menus" extension

[LilyMakesThings]

'All Menus' creates a category in the block palette with every menu of every Scratch category as well as loaded extensions.

Some notes about this extension:

• If the user has no other extensions loaded, the blocks from this extension are 100% compatible with Scratch.
• The extension won't save to projects because you can't technically drag extension-created blocks from the extension, as there aren't any.
• As a result of the previous statement, changes made to this extension won't be "breaking" changes. This can be deleted at any time.

[yuri-kiss]

i like this idea

[LilyMakesThings]

In theory the "refresh blocks" button could be removed; this refreshes automatically whenever an extension is loaded anyway.

[ClaytonTDM]

im having too much fun with this

[LilyMakesThings]

This extension has had a full rewrite, it no longer uses icky injection code.

[ClaytonTDM]

HELL YEAH

[ghost]

Thank you Lily for adding this