Correct code that was not correctly using the CFE_SB_ValueToMsgId or
CFE_SB_MsgIdToValue conversion wrappers where required to do so. This
should be used whenever the value is intentionally converted to/from
an integer.  The CFE_SB_MsgId_t type should not be assumed to be
an integer in nature.

Historically the CFE_SB_MSG_ID_INVALID constant was defined as 0xFFFFFFFF/-1,
where 0 was considered valid.

Although 0 is indeed valid for the first word of a CCSDS primary spacepacket header,
it is not actually valid for use with SB.  Because SB is now more decoupled from CCSDS
header definitions, there are a number of advantages to using 0 instead of -1, as
it is more passively safe:

- Objects which are cleared as part of normal BSS clearing will be set invalid
- Objects which are memset to zero will be set invalid

In contrast, when the invalid value is nonzero, objects which are memset/cleared
are valid by default, and must be actively set invalid to be safe.

This makes CFE_SB_MsgId_t to be a safe wrapper around CFE_SB_MsgId_Atom_t,
such that the values cannot be silently/implicitly interchanged with other
integers.

This enforces that the MsgId/Value conversion helpers must be used when
conversion to/from integers is intended.