FontFamily: Fix server-side attribute registration via typography support

[aaronrobertshaw]

Related:

• Locking: ServerSideRendered block error #40461
• Block Locking: Register the 'lock' attribute on the server #40468
• Archives: Add typography support #43935
• Tag Cloud: Add typography supports (except font size) #43452

What?

Ensures the fontFamily attribute is registered for block types on the server side as well. This fixes a 400 error when attempting to change the font family for a server-side rendered block in the editor e.g. Archives, Tag Cloud etc.

Why?

The attribute registration should be there in the server-side typography block supports as per fontSize etc. Fixing this error also unlocks typography support adoption for server-side rendered blocks.

How?

Adds fontFamily to the block type's attributes when the block has font family support.

Testing Instructions

1. Add typography support to a server-side rendered block e.g. Archives. (see block.json snippet below)
2. Within the editor, add the block you adopted typography support for e.g Archives
3. Within the inspector controls sidebar, switch to a new font
4. Note the 400 error in the dev tools console
5. Checkout this PR and repeat the process
6. The font family should successfully change without any error

		"typography": {
			"__experimentalFontFamily": true
		}

Screenshots or screencast

Before	After
Screen.Recording.2022-09-07.at.5.59.50.pm.mp4	Screen.Recording.2022-09-07.at.6.00.33.pm.mp4

[Mamaduka]

It works like a charm ✅ No more 400 error when applying this patch.

[t-hamano]

@aaronrobertshaw
A ticket related to this issue awas reported in WordPress core:
https://core.trac.wordpress.org/ticket/56678

Should this PR be backported?