Use the attached atttribute's location as the location of the macro,
rather than the location of the declaration it's attached to. Also add
the kind and name of that declaration to the note itself.
Introduce a new key `generated_buffers`, which
stores an array of generated buffers. These
include the buffer text, as well as its original
location and any parent buffers.
While here, also fix rdar://107281079 such that
only apply the filename fallback logic to the
pretty-printed Decl case. We ought to remove this
fallback once the editor can handle it though.
rdar://107281079
rdar://107952288
