Mozapkpublisher

Fixed
* Focus and Klar were sent in the same transaction, which cannot happen.
* False positive exception about multiple architectures

Removed
* `update_apk_description.py`: https://l10n.mozilla-community.org/stores_l10n/ is now retired making the script useless.
* `get_l10n_strings.py`: Automation hasn't used this script since [Bug 1560876](https://bugzilla.mozilla.org/show_bug.cgi?id=1560876). Moreover, like `update_apk_description.py`, this script doesn't work anymore.
* Exceptions `TranslationMissingData`, `NoTranslationGiven` which aren't used anymore

Added
* Any track can now be targeted with rollout

Changed
* Using `track="rollout"` is now deprecated (specify the target track instead)
* Uses RAII to represent operations that require an "edit"

Removed
* `--skip-check-package-names`. When pushing or checking an APK, expected package names must always be provided

Changed
* `EditService` now calls the Google Play API v3
* Fennec Beta can now match 68.Y pattern

Fixed
* Support new GP error when an APK is uploaded

Removed
* `push_apk.py` does not upload strings (like `description` or `whatsnew`) because https://l10n.mozilla-community.org/stores_l10n/ is about to be removed. `update_apk_description.py` remains in case we still want a manual upload while `stores_l10n` is around

Added
* Fennec ARM64 push on Release.

Changed
* `push_apk` doesn't error out anymore if an APK has already been uploaded

Removed
* Python 3.5 support