Draft: Add readout and frontend link functionalities and link-tests.

AIM

Add new stub and stub model for readout boards. The new DAQBoardStub class added along with the corresponding DAQBoardStubModel followed by an update to the SystemStubModel.

ASSOCIATED CHANGES

• Begin adding unit tests for stubs.py in tests/stubs/ for the base stub classes. Unit tests for only DAQBoardStub added for now.
• Unit tests for the pydantic model classes will be skipped due to redundancy with unit tests in tests/config.
• Add unit tests to tests/config/test_parse_system_file__.py for the added dth_boards, links and link_settings.

OTHER MINOR CHANGES

Split the unit tests file for parse_system_file() based on internal functions. In the directory the test/config the unit tests in test_parse_system_file__.py are now split with the addition of test__parse_link_operating_mode__.py , test__parse_link_port_selector__.py , test__parse_link_settings_section__.py and test__parse_multiple_system_files__.py.

This results in some associated changes with

• creation of tests/testutils.py - The functions for temporary path are in a utility function and not the pytest inherent conftest.py.
• changes to tests/conftest.py - Removal of the functions that were moved to the file above.
• creation of tests/config/conftest.py - For fixtures shared between the unit tests.
• changes to tests/config/test_parse_parameter_file__.py - The import statements need to be changed due to the shuffling of globally defined functions between files.

This was necessary to reduce the file size of tests/config/test_parse_system_file__.py.