Add SourceFileGenerator.GeneratedDeps()

Add SourceFileGenerator.GeneratedDeps()

To clean up unnecessary dependencies when using generated headers,
GeneratedDeps() should return a single file from every build entry.
GeneratedSourceFiles() used to be used from this, but now if you create
one build rule with multiple outputs, it's valid to only return a single
output file.

In this case, ModuleBuild is called once per source file, each
outputing a single output file, so all of them still need to be listed.

Bug: 73745773
Test: diff out/soong/build.ninja
Test: diff out/soong/Android-aosp_arm.mk
Test: rm -rf out; m
Change-Id: I073e3be7ecd9545f4002ad94d3da44f1a6652baa