Android: Android studio single module per target

Existing users can continue to split modules by gn targets by passing
--split-project to generate_gradle.py, although that flag will not
receive the same maintenance going forward, consider it deprecated.

This coalesces java and resource dependencies into the same build.gradle
file for each apk and junit target specified (test apks still get folded
into the apk_under_test target).

Speeds up sync/builds by 10x to 1-3 seconds. Paves the way for using
more of android studio's build steps, since they'll now take 1-3 seconds
rather than 10+ seconds each time.

BUG=620034

Review-Url: https://codereview.chromium.org/2708133002
Cr-Commit-Position: refs/heads/master@{#453257}
2 files changed