Add Font Features, Languages, and Name IDs on GlyphTypeface

[stevemonaco]

Is your feature request related to a problem? Please describe.

Querying the capabilities and informational data of a font is not directly supported by Avalonia. Besides apps that load fonts at runtime, such support could also open up new avenues for DevTools improvements.

Describe the solution you'd like

These should be added to GlyphTypeface:

• Feature is exposed by HarfBuzzSharp and exists as FontFeature(Collection) in Avalonia.
• Language is exposed by HarfBuzzSharp.
• Name IDs (OpenTypeNameId) are not exposed and need to be added to HarfBuzzSharp's Face via hb_ot_name_get_utf8.

Describe alternatives you've considered

No response

Additional context

Online tools such as https://fontdrop.info/#/?darkmode=true exposes this information in a usable way. This is sufficient for working with fonts with characteristics known at compile-time and may help others until Avalonia provides better information.

[Gillibald]

#15837