fix(python): Fix Series -> Expr dispatch for @property methods

[stinodego]

This is a bit of an ugly patch, but it was impossible to define a @property method on the Expr side. This is a workaround.

For context, I was trying to define an ordered property on the categorical namespace when I ran into this.

Overall I am not really happy with how the 'dispatching' worked out. The piece of code that takes care of it is too complicated for what it actually does. Anyway, that's a worry for another time, I guess.

[ritchie46]

Not related to this PR, but touches the same topic:

I haven't really looked at the dispatch code myself. Now I see the loop. Do we loop trough all methods on every expression dispatch? Is this something we can cache?

[stinodego]

Not related to this PR, but touches the same topic:

I haven't really looked at the dispatch code myself. Now I see the loop. Do we loop trough all methods on every expression dispatch? Is this something we can cache?

This only happens once, I believe it happens on import.

[ritchie46]

Cool, thanks!