Use Sources.bp for building

Reference Sources.bp from Android.bp, so that they are used as build
files.

Sources.bp is separate from Android.bp as it was migrated from the
Android.bp files in the old code location. They can be merged into the
main Android.bp file (or removed by removing the filegroups) after the
migration is done.

Also remove references to the AIDL filegroups, as files are now merged
into the common framework/aidl-export directory which is used as include
directory for aidl source generation already, so they do not need to be
referenced separately. framework/aidl-export can contain AIDLs for S-
API classes that became updatable API in T (the contents of
framework-t), as they are the same as any other API class for the
purposes of AIDL code generation: it's OK for any S+ code to reference
S+ API classes.

Finally, fix reference to mByteStream in IpConfigStoreTest. It was
already wrong but did not break the build because the test was not being
built in the old location.

Bug: 222234190
Test: TH
Merged-In: I1fe5091361c7766dc7b6b4fb8c7b62d403e950bb
Change-Id: If738f607be84b3d7e2045a83a4d2976ed0d4e188