Baseline existing API lint warnings

We are making warnings behave as errors (i.e. break the build).
Rather than fixing all the current warnings, just baseline them.

This CL is the result of
$ m
$ cp \
out/soong/.intermediates/frameworks/base/system-api-stubs-docs/android_common/api_lint_baseline.txt \
frameworks/base/api/system-lint-baseline.txt
$ cp \
out/soong/.intermediates/frameworks/base/test-api-stubs-docs/android_common/api_lint_baseline.txt \
frameworks/base/api/test-lint-baseline.txt"

Bug: 154317059
Test: m
Change-Id: Idf8f7dbcaa1c136781175fd5e66eed3525d21722
Merged-In: Idf8f7dbcaa1c136781175fd5e66eed3525d21722