Adds different font-sizes and line-heights for the custom
font-size UI. The custom font-size preference options are now:
1. Compact - 14px font-size & 22px line-height
2. Standard - 16px font-size & 24px line-height
3. Open - 20px font-size & 26px line-height
This removes the "xl" font-size option
(`vector-feature-custom-font-size-3`) and it's related i18n messages,
and changes the remaining message to match the new options.
The default font-size, when the custom font-size feature is disabled,
is "compact".
Bug: T351693
Change-Id: I5975a78ce7327f314fd55de55c222ac08d801fbd
Notes:
* This is functional but intentionally not designed until the design
has been finalized.
* A feature flag is added that swaps out the limited width toggle with
a settings cog
* The preferences module is kept in a separate ResourceLoader module
(skins.vector.clientPreferences) to make it more portable for
when we eventually want to add it to Minerva as well.
* Intentionally have not focused on non-jS version given we will
likely revise this again in a future version/upstream to core.
Bug: T345363
Change-Id: I0c793b73e0676e32f031c6168c292f63908c72e3
