Implement clickable URLs in asset library descriptions

[KoBeWi]

Godot version

c2a616f

System information

W10

Issue description

If an asset has links in the description, they can't be clicked nor copied. Example:

Steps to reproduce

1. Open AssetLib
2. Go to InterpolatedCamera3D asset
3. Notice the links
4. Try to open them

Minimal reproduction project

No response

[Calinou]

The description Label needs to be converted to use RichTextLabel and parse URLs automatically.

Eventually, we'll need a Markdown -> RichTextLabel parser as Markdown is allowed in descriptions in the new asset library.