Update C++ Attitude Filter Interface

[kylekrol]

Update C++ Attitude Filter Interface

Fixes #186.

Summary of changes

• Update the attitude estimator interface for the UKF implementation.
• Removed old attitude estimator tests.
• Added simple tests for the attitude estimator struct constructors.
• Updated the lin module.
• Added a PSIM macro for all builds in the PSim repository. This could help us change visibility for testing only within the PSim itself and avoid effecting flight software.

There is a ton of future work still to be done with this PR and it is documented in these tickets: #187, #188, #189, #190, #191.

I'm still for merging in just the interface without the actual implementation to give FSW more time to integrate it and because literally nothing depends on the deleted code.

Ptest Effects

NA

Testing

See simple constructor tests.

Constants

NA

Documentation Evidence

See inline documentation.

[kylekrol]

It may be easier to review by checking out the branch locally and just scrolling through the three main files: include/gnc/attitude_estimator.hpp, src/gnc_attitude_estimator.cpp, and test/test_attitude_estimator/test_attitude_estimator.cpp.