Extend RecursionTracer to handle mutual recursion

[david-yz-liu]

Currently the python_ta.debug.RecursionTable context manager only works with a single function_name argument. However, there are cases where we may want to support mutual recursion like

def f(n: int) -> int:
    if n <= 0:
        return 1
    else:
        return 2 + g(n - 1)
    

def g(n: int) -> int:
    if n <= 0:
        return 1
    else:
        return 2 * f(n - 1)

Let's modify RecursionTable to take a list of function names to be able to trace. The table output format will likely need to be updated as well.