Rename files and change namespaces because of regarding ABIE’s as MBIE’s and BDT’s as MBT’s.

[peter-vermeulen]

We do not change the prefix bie and we only change the prefix bdt into mdt. The root schema remains basically the same, but imports mbie’s and mdt’s ABIE-schema becomes MBIE-schema; BDT-schema
becomes MDT-schema