platform agent test cleanup

- test_..._**with_rsn** files renamed to omit the **with_rsn** suffix (to avoid confusion as the tests are actually against our CI RSN simulator, not the actual RSN OMS endpoint).
- some obsolete test code removed
- unit tests for RSNPlatformDriver re-enabled and expanded
- other adjustments including workaround in a use of DotList in mission_executive

@edwardhunter please review/merge

@bobfrat please review