Inserter Component: Improving Stories

[SirLouen]

Why?

1. Currently Inserter block is not full testable without sample blocks
   https://wordpress.github.io/gutenberg/?path=/docs/blockeditor-inserter--docs
2. Also there is not a full behaviour with popup as we can see in the wild.

How?

1. Firstly, I mimic the behaviour of block-mover adding the registerCoreBlocks so we can see real content within the inserter.
2. Secondly I add a "Full Inserter" story, similar to the QuickInserter one, which mimics the popup element that happens within the editor.

This is going to be particularly useful to showcase in tickets like: #74920

Testing Instructions

1. Run the storybook
2. Go to the Inserter
3. Check for the Full Inserter, it should open, close with the X, close when clicking outside.

Testing Instructions for Keyboard

1. It should also close with ESC

Screenshots or screencast

[github-actions]

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[Mamaduka]

This will be invoked for this story alone, right?