GitLab

Building with Android 3.6.1

fixes gitlab-org/gitter/gitter-android-app#122

Includes https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/112

 - Log version code/name for easier association
 - Bump `versionCode` by `40` so it is high enough than current builds, `40 + 48` -> `88`
 - Add `ensureContainer` job which will build a container for the branch if it doesn't exist

https://gitlab.com/jlenny/gitter-android-app/-/jobs/130568715

```
build.gradle:63: Error: Version must be at least 10.2.1 when targeting O [GradleCompatible]
implementation "com.google.android.gms:play-services-gcm:9.6.1"
```

As discussed in https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/5#note_122709696

We convert the jks file to hex and store in a project secret variable(environment variable).
Then when running, we take the hex varible and convert it back to a binary file via `xxd`

Binary to Hex (for storing the secret project variable)
````
xxd -p gitter-android-app.jks
```

Hex to Binary
```
echo "$signing_jks_file_hex" | xxd -r -p -
```

---

Also fix Google Play API key not being saved in place we were trying to look it up, ~/google_play_api_key.json

We updated to Android Build tools 28 in https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/6

This was spurred on because of the requirement to use API >26 to upload to the Google Play store, https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/5#note_122717509

Part of https://gitlab.com/gitlab-org/gitter/gitter-android-app/merge_requests/4

Previously it wouldn't build locally, only in CI.

Now it builds both locally and on CI

Part of open-sourcing Android, https://gitlab.com/gitlab-org/gitter/gitter-android-app/issues/8

Secrets now stored in untracked `secrets.properties` which is read by `app/build.gradle`

Part of https://gitlab.com/gitlab-org/gitter/webapp/issues/1876