Modify extractStubsSourceInfoFromDep to respect RELEASE_HIDDEN_API_EXPORTABLE_STUBS flag

Currently, extractStubsSourceInfoFromDep always return the "everything"
stub artifacts. This change modifies such behavior so that the
"exportable" artifacts are set when
`RELEASE_HIDDEN_API_EXPORTABLE_STUBS` build flag is set to true.

Test: m nothing --no-skip-soong-tests
Bug: 348370901

Change-Id: I1cf0ff7a63c8a580c3553a817ca303d6e8734a2a