Alphabetically sort blocks in global styles

[dsas]

What?

The blocks in global styles firstly list the core blocks in an undefined order, and then the non-core blocks also in an undefined order. This change lists the core blocks alphabetically by title, and then non-core blocks alphabetically by title.

Why?

This gives a more predictable order of blocks when using global styles. It's a quick initial solution for #44840

How?

The core blocks are sorted by title according to locale specific sorting rules, and then non-core blocks are sorted in the same way and then returned together.

Testing Instructions

0. Install a plugin which gives non-core blocks, e.g. jetpack or coblocks.
1. Open the site editor
2. Open the styles menu on the right to open the global styles sidebar
3. Press 'Blocks' at the bottom of the sidebar
4. Notice the core blocks are listed in alphabetical order followed by non-core blocks in alphabetical order
5. Search for blocks, the results will also be returned in alphabetical order.

Screenshots or screencast

Before	After

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[apeatling]

Tested and confirmed that blocks in global styles are now in alphabetical order. Checking through the rest of the project this also seems to be the accepted way to sort. 👍

[jasmussen]

Yep, let's go with this. If we need curation we can do better (such as subheadings) than just arbitrary reordering.

[richtabor]

Gave this a once-over; alphabetizing works well here.

What's the reasoning on sorting non-core blocks separately?

[dsas]

@richtabor It sorts core blocks above other blocks currently. I don't understand why so I opted to preserve that behaviour in this PR, assuming there's a good reason.