Fix conformance regressions due to type and region changes.

Compress flatbuffer JSON files for conformance to allow while_loop
tests to fit in the 30MB file size limit.
Do not include new SHAPE type in usable DTypes so that selection of
ERROR_IF tests are not changed.

Also enable strict json mode for flatbuffers.

Change-Id: Id89a9963244c34769a4662f9951adde0aa3334d9
Signed-off-by: Jeremy Johnson <jeremy.johnson@arm.com>