Fix #422, implement dispatcher pattern for CF

Checklist (Please check before submitting)

[x] I reviewed the Contributing Guide.
[x] 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 Move message identification, validation, and routing to a separate source file per the recommended CFS app patterns.

Fixes #422

Testing performed Build and run all tests

Expected behavior changes Nothing external

System(s) tested on Debian

Contributor Info - All information REQUIRED for consideration of pull request Joseph Hickey, Vantage Systems, Inc.

nasa / CF