Refactor Font configuration and import UI, and Font resources.

[bruvzg]

Supersede #61406, Supersede #61473, Supersede #62065

• Merges all import time properties of Font and FontData into single Font resource. Including fallback font list and pre-rendered glyphs (different sets of pre-rendered glyphs can be selected for different sizes/variations).
• Adds FontVariation subclass to access OpenType variations, embolden/slant, font collection face index, OpenType features, and extra spacing and allow fallback override in runtime.

New font resources structure:

FontVariation screenshot:

[sairam4123]

Can font size be changed for per control node?

[bruvzg]

Can font size be changed for per control node?

It's already possible with the Theme properties and not changed by this PR.

[reduz]

It looks good to me, but I have the feeling that using FontBase all across the codebase probably is a bit unnecesary since we don't do this with other resource types (like Texture2D, AudioStream, Mesh, etc).

Maybe we should do

FontBase -> Font (abstract)
Font -> FontFile or VectorFont or maybe just ScalableFont (which is the technical name for OTF/TTF/etc).

[bruvzg]

FontBase -> Font (abstract)
Font -> FontFile or VectorFont or maybe just ScalableFont (which is the technical name for OTF/TTF/etc).

OK, I'll change it to Font and FontFile (the same class is used for bitmap fonts, so it's not always scalable).

[reduz]

@bruvzg Alright, sorry for the change request and great job!, realized we were no longer using resources with "Base" naming in 4.0 too late so my mistake.

[bruvzg]

I'll change it to Font and FontFile

Done.

Requested changes done, and @reduz approved the follow-up #62139 so it should be good to go.

[akien-mga]

Looks great!

[akien-mga]

Thanks!