Deprecate loadMemoryFromFile SFC Details (#2986)

Deprecate implementation details related to the loadMemoryFromFile API.
Specifically, deprecate the Chisel-level annotation and the SFC
transform while preserving the Chisel APIs.  The Annotation will, after
Chisel 3.6 be made private and the transform will be deleted.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>