Add brotli decoder and WOFF2 support.

[bruvzg]

Adds brotli decoder and enables WOFF2 font support.

Note: Adding decoder increase binary size by about 100 KB, but converting all editor and default theme fonts to WOFF2 can decrease it by 4.4 MB. Tested by using https://github.com/google/woff2 on all included fonts, not included into this PR, since quality of conversion need to be tested first.

[akien-mga]

Might be useful for the JavaScript platform @Faless @Calinou :)

[Calinou]

For reference, WOFF1 support was exposed in #52052.

This is definitely a good thing to have, especially since many web fonts are now distributed in a WOFF2 format only (and using it in another format requires manual conversion).

Having a Brotli decoder will also make it possible to implement support for transparent Brotli compression in HTTPRequest (similar to gzip).

[akien-mga]

Thanks!

[Calinou]

Would it make sense to backport WOFF2 support to 3.x? We can likely get similar benefits for editor binary size there. However, the export templates won't benefit from it as no DynamicFont is embedded in export templates in 3.x. That said, anyone using a DynamicFont in their project can use a WOFF2 conversion tool and probably offset the increase in binary size this way.