Update styling of wp-admin form elements to match the WordPress design system as established by the block editor

[fabiankaegy]

Over the past several years, ​the WordPress design system has been updated quite a bit. All these new design choices have been implemented in the block editor first using the @wordpress/components design system as the source of truth.

Whilst the eventual goal is to actually leverage that react component library to also power all of the admin interfaces, a first step would be to realign the styling applied to the individual components.

This is a larger effort and, therefore, best broken up into several small incremental updates.

To start, I would suggest we look at the button & form elements. I tried to handle them in isolation, but there are so many places where buttons render next to select elements, for example, that they really need to be handled at the same time.

Trac ticket: https://core.trac.wordpress.org/ticket/62933

[audrasjb]

Related: #62864

[audrasjb]

Thanks for the ticket and PR!
At a glance this ticket looks a lot like a duplicate of #62864, isn't it?
Pinging @karmatosed too ;)

[fabiankaegy]

Duplicate of #62864.

@audrasjb you are completely right :facepalm: I even talked to @karmatosed about it before either of us started working on it. I just wansn't able to find their ticket/patch. This one can get closed out as a duplicate :)

[audrasjb]

Ok thanks for the feedback!