aapt2: Preserve annotation parameters for SystemApi.

SystemAPI can now be parameterized. Note that this change preserves
the content of the annotation params without attempting to interpret
them in any way. This means that references to types outside of
java.lang must be fully qualified.

Test: atest aapt2_tests
Bug: 147581540
Change-Id: I0630fb1c7c7a7f5918ff2dca32fb8e078b367751