Prerequisite for making `adb root` wait for the device that it told to
restart to disappear: the client needs to know which transport to wait
on.
Bug: http://b/124244488
Test: manual
Change-Id: I474559838ad7c0e961e9d2a98c902bca3b60d6c8
Rearrange some files while we're doing this.
Bug: http://b/71721338
Test: manually ran adb on windows
Change-Id: Ie47bda82279e4b9521505ad0353bf9ef649fc7d7