This PR builds on [AC##9024][1], and implements setting the Nimbus endpoints from [a secret set at build time][2].
For production use, this requires a secret named `nimbus_url` to be put into CI.
Note: Nimbus is currently behind a feature flag.
If developers wish to use a Nimbus server for local development, you can set the url by adding an entry into local.properties, e.g.:
```
nimbus.remote-settings.url=https://settings.stage.moz4ws.net
```
Without setting server, Nimbus will be able to function, except no experimental definitions will be fetched, and features under experiment will be configured as if not enrolled in the experiment.
[1]: https://github.com/mozilla-mobile/android-components/pull/9024
[2]: https://groups.google.com/a/mozilla.com/g/android-components-team/c/lAGVKQy8aiA/m/rY3uGAwhBAAJ
New API (installBuiltIn/ensureBuiltin) requires
- Gecko IDs and new permissions
- Extension will only be re-installed if it has a new version
This includes a gradle task to automatically generate a
new version in manifest.json for every build so we don't
forget to update the version and end up with changes that
are never applied.