Squashed 'external/devlib/' changes from 7276097d4..3e45a2298

3e45a2298 collector/dmesg: Handle non-matching regex
3c37bf3de target: Make Target.make_temp() async-compatible
52281051b target: Run Target.disconnect() upon process termination
7714acc89 target: Make Target.disconnect() steal current connections
f5f06122f target: Provide context manager API for Target
c9b539f72 Validate cgroups_run_into has taken effect
a28c6d7ce utils/android: Use subprocess.DEVNULL where appropriate
b8292b1f2 utils/android: Log error in _ping()
94f1812ab Create LICENSE
71d1663b2 tools/android: Address review comments on PR#668
492d42ddd target: tests: Address review comments on PR#667

git-subtree-dir: external/devlib
git-subtree-split: 3e45a2298e2ba7da25e27ebe7651aa48f2fd62b5