4693: Fennec data migration scaffolding r=pocmo a=grigoryk

This is going to be a rolling PR for a little bit, until this is ready to land.
Companion Fenix PR: https://github.com/mozilla-mobile/fenix/pull/5878

Workflow for testing it:
- fetch an ESR68 build from TC: https://tools.taskcluster.net/index/gecko.v2.mozilla-esr68.signed-nightly.nightly.latest.mobile
- re-sign it using a local debug keystore:
  - `zip -d target.apk "META-INF/*"`
  - `~/Code/mozilla-central/mobile/android/debug_sign_tool.py target.apk`
- enable auto-publication workflow for a-c in fenix
- assemble fennecProduction version of Fenix (built against this branch, see auto-publication)
  - `./gradlew assembleFennecProduction`
- sign it using keys used to sign fennec esr apk (otherwise we won't be able to overwrite one with another):
  - `~/Code/mozilla-central/mobile/android/debug_sign_tool.py app/build/outputs/apk/geckoBeta/fennecProduction/app-geckoBeta-x86-fennecProduction-unsigned.apk`
- install fennec esr apk build
- generate some profile data for migration (sign-into fxa, browse around, etc..)
- install fenix build: `adb install -r app/build/outputs/apk/geckoBeta/fennecProduction/app-geckoBeta-x86-fennecProduction-unsigned.apk`

TODO:
- currently needs https://github.com/mozilla/application-services/pull/1942

 to work
- add separate migration versioning for history and bookmarks; currently the whole thing is versioned
- add migration tests
  - in fennec, we have a bunch of "schema migration" tests that operate over older versions of browser.db
  - this is a good approach here as well - we can run migration code in tests against a few test db files, that exercise various history/bookmarks configurations and try multiple schema versions
- improve the workflow around this, it's quite tedious currently

Co-authored-by: Grisha Kruglov <gkruglov@mozilla.com>