Until now it was assumed that a serialized key is the PLAIN_CDR2
Big Endian encoding of a <TYPENAME>KeyHolder Object [DDS_XTYPES v1.3, 7.6.8]
(I.e. the same blob that computes the MD5 key hash).
Taking other DDS implementations as reference (e.g. Cyclone DDS), it
seems they are using a normal Payload containing a KeyHolder(<TYPENAME>)
Object [DDS_XTYPES v1.3, 7.2.2.4.7] as the serialized key.
The Key Holder Template (together with the Type1 and Type2
implementations) were updated to reflect this change.
A bug fix were the Key Hash was not reset on a 'PUSH_SERIALIZED_KEY'
opcode was also fixed (together with the testbench).
Templates with the pre-defined code hull for the reader_wrapper,
writer_wrapper, and key_holder were created.
A "cookbook" of how to expand this TEMPLATES to create type specific IDL
conversions was also added.
The "code generation" is kept general to allow a code generator to
automatically produce this wrappers in the future.
