C2MS13 — CCSDS Packet has mismatch in R/O for Subject/Fields

In the C2MS 1.2 spec for the CCSDS Packet Message, Table 8-72 specifies VCID & APID as required for the subject but in the 8-74 table VCID & APID are optional Fields.

Need a disposition on VCID. Note that VCID was required in 1.0, optional in 1.1/1.2 (except in the subject), so maybe make it optional for backward compatibility with 1.1/1.2.

APID should be optional everywhere, because it was added in 1.1, so can't force backward requirement here.

Note, too, that the description in the Subject for APID should say it comes from the APID field instead of the nebulous "From the Header".