android: move most avd logic into build/android/.

Makes handling the avd code significantly easier for build subtree
embedders.

This is a follow-up to crrev.com/c/1827248

Bug: 922145
Change-Id: I30957c13e99c7224dddfd201666af622ba855441
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1841935
Commit-Queue: John Budorick <[email protected]>
Reviewed-by: Andrew Grieve <[email protected]>
Cr-Commit-Position: refs/heads/master@{#703011}
14 files changed