support products that don't put build info on archive.mozilla.org

[willkg]

There's this issue from Buildhub asking to support Focus: mozilla-services/buildhub#500

There's bug 1552583 (https://bugzilla.mozilla.org/show_bug.cgi?id=1552583) asking to support Fenix.

Currently neither Buildhub nor Buildhub2 support products that don't use the same release process as Firefox. This issue covers figuring out how to support products that don't put build information on archive.mozilla.org.

[willkg]

We've got a rapidly increasing number of GeckoView-based products and it seems helpful to have an index of build information for them. Seems like we should tackle this.

I think we can either:

1. force those products to put build information on archive.mozilla.org in the right format and directory and then slurp it into Buildhub2, or
2. add users, API tokens, and an API for pushing build information into Buildhub2

I haven't given this much thought, but it seems like the second one is more flexible.

[willkg]

I've thought through this and talked out possible options with other people and we're not going to do this.

For now, to support other products, those products must publish buildhub.json files with the right schema on archive.mozilla.org.