Navigation: Add font size attribute

[Copons]

Description

Adds the font size style attributes (both named and custom) to the Navigation block.

How has this been tested?

Tested on macOS 10.15.2, Chrome 78, Gutenberg Docker environment, Twenty Twenty theme.

Screenshots

Before	After

Testing instructions

• Edit a post and add a Navigation block.
• Try changing the block's font size.
• Make sure the block looks as expected.
• Preview the post, and make sure the block looks as expected in the front end too.
• Repeat the previous steps, but this time check if the font size custom attribute work as expected.

Types of changes

New feature (non-breaking change which adds functionality)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. .

[Copons]

Ah, for crying out loud, I sat on this for too long and we already have #19108 open... 😓

I guess this is still valuable for the font size part though.

(Discussing at #19108 (comment) about dropping the first two commits of this PR, and only keep the font size parts)

[noahtallen]

The code looks good to me. It also tests great locally!

One thought -- I notice the paragraph block uses a new inline mechanism for font. Should we add this too?

[Copons]

The code looks good to me. It also tests great locally!

One thought -- I notice the paragraph block uses a new inline mechanism for font. Should we add this too?

@noahtallen Oh, I missed that!
I'm putting this in WIP so that I can check it out and see how to integrate it here.

EDIT: Ah, never mind, that comes from CoBlocks. 🙂

[noahtallen]

oh my 😁 my bad! That's some good stuff. We should have that

[noahtallen]

Who should we ping on this? I think it should be ready to go. I can't think of any reason to not have it.

[Copons]

@noahtallen I'm not sure, but the codeowners have been automagically pinged already. 🙂

[talldan]

This is working nicely, thanks for the addition.

It'd be great to remove that one classname before merging.

[talldan]

The blocks-font-size class doesn't seem to do anything, so I think it'd be good to remove it. I did a search of the codebase and it looks like it's only used in end-to-end tests in the paragraph block.

Update: I put together a PR (#19208) to remove it entirely from the codebase. It looks like there used to be styles for this class in the paragraph block, but they've been removed. The e2e tests were updated to use a different classname in that PR.

Suggested change

	<PanelBody title={ __( 'Text Settings' ) } className="blocks-font-size">
	<PanelBody title={ __( 'Text Settings' ) }>

[Copons]

Oh good catch! Removed in 6789b26.

I'll merge as soon as tests are clear!