Let's create a non-build variant of brand.ftl. That should be helpful in a variety of ways, most prominently it'll help to make language packs independent of update channel.

I'm explicitly not bothering about brand.dtd nor brand.properties, or MOZ_APP_DISPLAYNAME.

The idea is to:

• Create a built-in Fluent function like PLATFORM, say BRANDING.
• Port brand.ftl into browser/browser/branding/brandings.ftl
• Drop the use of brand.ft, replacing with brandings.ftl where needed

The reason to use the existing brandings.ftl is that they're already serving that purpose, and we're reducing the number of fluent files in a context by 1 many brand-dependent contexts, I guess.

Risks: Performance, at the very least. If so, I'll need to pass this on to someone that can help on the perf side.

Depends on D53817

Assigning a priority to get this out of the triage list. It looks like this is being currently worked on, so P1, but please adjust as necessary.

I think this is still something we should eventually do, but after the move to fluent.rs, exposing globals like this doesn't work anymore.

I don't intend to drive this one forward. Zibi, do you want to pick this up?

Anyway, unassigning myself, resetting priority. The latter as its been set based on me working on this, so that's not justified anymore right now.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.