BpfCoordinator: Add an option to choose which raw bpf map to dump

Make that tethering dumpsys can choose which map to dump.
The related functions in BpfCoordinator and its test are refactored
into template functions. This is used in the following commits which
will dump stats map for testing.

Bug: 227159997
Test: atest TetheringCoverageTests

Change-Id: I23d747543d16a971773c132b60227eb3f42efe25
3 files changed