Limit the number of outstanding DNS queries by UID

Test: system/netd/tests/runtests.sh
Test: run netdutils_test on marlin:
    [----------] 3 tests from OperationLimiter
    [ RUN      ] OperationLimiter.limits
    [       OK ] OperationLimiter.limits (0 ms)
    [ RUN      ] OperationLimiter.finishWithoutStart
    [       OK ] OperationLimiter.finishWithoutStart (3 ms)
    [ RUN      ] OperationLimiter.destroyWithActiveOperations
    [       OK ] OperationLimiter.destroyWithActiveOperations (1 ms)
    [----------] 3 tests from OperationLimiter (6 ms total)
Bug: 79674503
Change-Id: I5f11f0ed6b6f2479921d90a919d17dfd7b7f5788
Merged-In: I5f11f0ed6b6f2479921d90a919d17dfd7b7f5788