Running `generate_ref_files.py` does not work as expected

[bocchino]

When I run python tests/generate_ref_files.py $FPP_DIR, I see this:

-      enum State: U8 {
-        @ The uninitialized state
-        __FPRIME_UNINITIALIZED
-        IDLE
-      }
-

It looks like a bug in the test code generation that predates #24.

[bocchino]

I think the issue is that the Python model includes the state machine enums that are generated by the analysis and are not in the user-supplied source. We need to either generate this code when generating the reference output, or we need to remove it when generating the test output.

[bocchino]

For now the workaround is to manually restore that code that gets deleted when you generate the reference output.

[bocchino]

To fix it, I think we should add a switch to fpp-to-fpp a.k.a. fpp-format (see nasa/fpp#1073) to introduce the state machine enums before writing out the FPP source. The testing in this repo already uses fpp-format to generate the reference output.