Add transport affinities for flex scheduling.

Switch the flex network behavior from unmetered vs metered to looking at
network transports. Transport affinities indicate which transports are
preferred for running jobs, and which ones the system should try to
avoid, if possible. By default, when flex scheduling is enabled, the
system will avoid running jobs on the cellular network and prefer
running jobs on wifi and/or ethernet networks.

Watches tend to send most traffic over the bluetooth network. However,
there are plans to modify job network traffic in other ways for watches.
For now, watches will be excluded from network flex scheduling until
those plans are resolved.

Bug: 236261941
Bug: 299329948
Bug: 299346198
Test: atest CtsJobSchedulerTestCases:ConnectivityConstraintTest
Test: atest CtsJobSchedulerTestCases:FlexibilityConstraintTest
Test: atest frameworks/base/services/tests/mockingservicestests/src/com/android/server/job
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/job
Change-Id: I675d72b18ae6ddc43fb1503d481ff9bb56c2dcb6