Add hashing and equality check for AthConfigFlags

People are coming up with interesting ways of memoizing component accumulator configuration code. It might be a bit more robust to use rlu_cache for this, e.g.

@lru_cache(5)
def getSomethingCfg(cfgFlags):
    return someExpensiveOperation()

But that requires making the inputs hashable.

If someone tries to hash the config flags without calling lock() this will throw an exception, since hashed objects should be immutable.