Change Monitor dict to a proper class

[halldorfannar]

I suggest we do this in the next major release. Since Monitor now contains heterogenous types (int, bool, str) it feels quite messy to have it a dict. When converting it to a class we could also make the attributes read-only, simply by having it inherit from a NamedTuple. I think this would be quite neat. But it's just a suggestion.

[BoboTiG]

I like the NamedTuple idea!

But even if we break typing compatibility, could we still provide a dict getitem fallback?

[halldorfannar]

Yes, we could. We would just have to be careful to not break the basic tuple indexing. The implementation would be something like this:

def __getitem__(self, key: Union[str, int]):
        if isinstance(key, str):
            # Map the string key to the attribute
            try:
                return getattr(self, key)
            except AttributeError:
                raise KeyError(key) from None
        # Otherwise, fall back to standard tuple indexing (0, 1, 2...)
        return super().__getitem__(key)