libtimeinstate: add more tests

Check reported values to confirm that getUidCpuFreqTimes() and
getUidsCpuFreqTimes() are behaving reasonably.

Also revise RemoveUid test to create and then delete map entries for
an unused UID rather than UID 0. getUidCpuFreqTimes() is only meant to
be called when an app is uninstalled, and calling it with a UID that
has running tasks creates data inconsistencies that can cause the new
tests to fail. Since the revised test needs to directly manipulate the
BPF map in order to add a fake entry, move some definitions from
cputimeinstate.cpp into a header file to make them available for the
test.

Test: libtimeinstate_test passes
Bug: 78498733
Change-Id: I1587b1c7db870343ff863f2156b2a810d8ace915
Signed-off-by: Connor O'Brien <connoro@google.com>
(cherry picked from commit ff7bf701)
Merged-In: I1587b1c7db870343ff863f2156b2a810d8ace915