Apply-update: Script to apply updates to device

<Development workflow for any project in the platform and build with 'm' to create the images>

Build:

$m apply_update

$ apply_update --help

Update the device to the current build in $OUT:
$ apply_update

Update the device, but skip flashing static partitions (see --help):
$ apply_update --skip-static-partitions

Update the device and wipe user data:
$ apply_update --wipe

Performance:

a: Default update without any paramenters: Update takes ~30-40 seconds.
b: With --skip-static-partitions its < 20 seconds

Bug: 371304627
Test: Test development workflow:

1: m libsnapshot && m -j
   apply_update

2: m snapshotctl && m -j
   apply_update --wipe

3: m virtmgr && m -j
   apply_update --skip-static-partitions

4: m crosvm && m -j
   apply_update --skip-static-partitions

Change-Id: Iff2c774ef83bc67601cc978e2e3ceea355a5482f
Signed-off-by: Akilesh Kailash <akailash@google.com>