Inconsistencies in `pyOpenFAST` code

[andrew-platt]

Problem description
In the pyOpenFAST code, there are inconsistencies in the usage of the OpenFASTInterfaceType. Several variables are duplicated in multiple places, such as:

• ERROR_MESSAGE_LENGTH: int = 8197
• DEFAULT_STRING_LENGTH: int = 1025
• ERROR_MSG_C_LEN

Related
Noted in #3065, but no time to fix there.

Remedy

• check files in python/pyOpenFAST for consistency in what is included in interface_abc.py
• check regression tests as well