The a-c side of this work is in https://github.com/mozilla-mobile/android-components/pull/6128
This switches Fenix to use `SyncableLoginsStorage`, which caches a connection internally
on first access, and doesn't expose any lock/unlock APIs at the public boundary.
* Upgrade to Mozilla Android components 15.0.0-SNAPSHOT
* Update findinpage integration to use browser-state
* Use new UseCases APIs after download migration.
Since we are now able to build against GeckoView Nightly and GeckoView Beta,
we should create the GeckoRuntime from a flavor-specific source set.
Creating the runtime is not covered by the AC abstraction and so API changes
in GeckoView Nightly can break the build and leaves us with no option to fix
it from a shared code base. Separating the creation of GeckoRuntime
allows us to adapt individually and also to configure the runtimes
differently.
Grisha Kruglov