mobile: build libuplink aar

[mniewrzal]

What: Add building libuplink-android.aar to Makefile.

Why: We need to automate libuplink-android and this change is part of larger task.

Please describe the tests:

• Test 1: none

Please describe the performance impact: none

Code Review Checklist (to be filled out by reviewer)

• Does the PR describe what changes are being made?
• Does the PR describe why the changes are being made?
• Does the code follow our style guide?
• Does the code follow our testing guide?
• Is the PR appropriately sized? (If it could be broken into smaller PRs it should be)
• Does the new code have enough tests? (every PR should have tests or justification otherwise. Bug-fix PRs especially)
• Does the new code have enough documentation that answers "how do I use it?" and "what does it do?"? (both source documentation and higher level, diagrams?)
• Does any documentation need updating?
• Do the database access patterns make sense?

[egonelbre]

If the building is happening in a temporary directory, do we need to ignore vendor dir?

[mniewrzal]

yeah, maybe its a good idea to do everything in tmp dir.

Done.