KVM: selftests: Test masked events in PMU filter

Add testing to show that a pmu event can be filtered with a generalized
match on it's unit mask.

These tests set up test cases to demonstrate various ways of filtering
a pmu event that has multiple unit mask values.  It does this by
setting up the filter in KVM with the masked events provided, then
enabling three pmu counters in the guest.  The test then verifies that
the pmu counters agree with which counters should be counting and which
counters should be filtered for both a sparse filter list and a dense
filter list.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20221220161236.555143-8-aaronlewis@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>