Refactor simulator functions to allow separate compile and run target…

[Risto97]

…s, which allows adding tests with CTest

[Risto97]

With this update, it is possible to create a compilation target without run target for modelsim, iverilog, xcelium, verilator using NO_RUN_TARGET argument.
Additionally, on subsequent calls to each of the functions, it is possible to create the run target.
Along with RUN_TARGET_NAME it is possible to specify the name of the created run target.

This is useful when creating CTest tests, in cases where different test scenarios are for example passed with $plusargs CLI arguments.
For example:

iverilog(${IP} NO_RUN_TARGET) # Create only compilation target

foreach(test_name hexfile IN ZIP_LISTS test_list hex_list) # Loop through list of cross compiled C tests
    iverilog(${IP}
        RUN_ARGS +firmware=${hexfile}               # Pass path to compiled hexfile to simulation
        RUN_TARGET_NAME run_${test_name}            # Create a target for running the hex file test
        )
    add_dependencies(run_${test_name} ${test_name}) # Make sure hex file is compiled before simulation is invoked
    add_test(NAME run_${test_name}                  # Create a CTest that will run the simulation target
        COMMAND make run_${test_name})
endforeach()