Use generic "cf_msgids.h" file that uses offsets from base MID

[jphickey]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I reviewed the CF README.md file to see if the feature is in the major future work.
• I performed a cursory search to see if the feature request is relevant, not redundant, nor in conflict with other tickets.

Is your feature request related to a problem? Please describe.
Currently, the example cf_msgids.h file supplied with CF (under platform_inc) is hardcoded, e.g.:

CF/fsw/platform_inc/cf_msgids.h

Line 33 in 557c132

#define CF_CMD_MID (0x18B3) /**< \brief Message ID for commands */

This presents some challenges for the user:

• at a minimum the user needs to modify this file in place (because the build script just points to this dir, there is no selection/override currently)
• it is not really possible to use different MIDs on multiple instances of CF running on a multi-CPU deployment.

Describe the solution you'd like
Use offsets from CFE_PLATFORM_CMD_MID_BASE and CFE_PLATFORM_TLM_MID_BASE like CFE framework does. For example:

https://github.com/nasa/cFE/blob/924b2be20a39f17355861396273856caccc8c89f/cmake/sample_defs/cpu1_msgids.h#L87

Thus the user only needs to specify the offset from the base (aka the "topic ID") in the mission_cfg.h file (which has global scope, not processor scope) and each CPU will automatically get non-overlapping MID numbers.

Describe alternatives you've considered
The alternative is to employ the generate_config_includefile cmake function to allow the user to specify this file per arch, but IMO the topicID/offset approach is simpler and more logical.

Requester Info
Joseph Hickey, Vantage Systems, Inc.

[skliper]

In theory you could just override as documented in nasa/cFS#403