Updates for Svc/ActiveRateGroup corresponding to UT cmake update for protected/private

[m-aleem]

Related Issue(s)	#3446
Has Unit Tests (y/n)	Yes - Existing
Documentation Included (y/n)	N/A

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Change Description

I locally updated fprime/cmake/settings.cmake to change -DPROTECTED=protected -DPRIVATE=private. This causes additional build errors beyond all our updates in manual code for PRIVATE->private and PROTECTED->protected due to auto-coded files which use PRIVATE, PROTECTED. This set of changes is associated with fixing Svc/ActiveRateGroup so that the UTs in this directory can build and pass.

Approach in this case was:

1. mv ActiveRateGroupTester.cpp ActiveRateGroupTestMain.cpp
2. mv ActiveRateGroupImplTester.hpp ActiveRateGroupTester.hpp
3. mv ActiveRateGroupImplTester.cpp ActiveRateGroupTester.cpp
4. Change ActiveRateGroupImplTester to ActiveRateGroupTester where applicable in files content of the files above
5. Change friend of ActivateRateGroup from ActiveRateGroupImplTester in ActiveRateGroup.hpp to ActiveRateGroupTester (to match friend class name pattern)
6. Use public (instead of protected/private) methods/members of ActiveRateGroup in ActiveRateGroupTestMain

Rationale

#3446

Future Work

1. Note that this PR does not include the update to fprime/cmake/settings.cmake itself - this will be done at the end
2. Note that this PR does not include re-naming the flight code <X>Impl to <X> (separate issue)