Fix #87, Change EVS_Register failure from SendEvent to WriteToSysLog

[thnkslprpt]

Checklist

• I reviewed the Contributing Guide.
• I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution
Fixes #87
CFE_EVS_SendEvent replaced by CFE_ES_WriteToSysLog on failure of CFE_EVS_Register.

Testing performed
GitHub CI actions (incl. Build + Run, Unit Tests etc.) all passing successfully.
Coverage maintained at 100%:

  lines......: 100.0% (1443 of 1443 lines)
  functions..: 100.0% (72 of 72 functions)
  branches...: 100.0% (525 of 525 branches)

Expected behavior changes
Failure can be successfully recorded somewhere even without the EVS now.

Contributor Info
Avi Weiss @thnkslprpt

[jphickey]

Minor update requested, but otherwise looks good! Thanks.

[jphickey]

I would recommend taking out these two assertions, no real need to assert that a function was not called. Also no need to add the global variable either.

[thnkslprpt]

No worries @jphickey
Removed those two.

[jphickey]

Looks good, thanks!