Support `create_index: bool` in `to_dataframe` to skip creating MultiIndex

[dcherian]

Is your feature request related to a problem?

stack lets a user skip creating a potentially expensive MultiIndex by passing create_index=False.

Describe the solution you'd like

We should support the same kwarg in to_dataframe for the same reason.

Describe alternatives you've considered

Expect the user to know that the MultiIndex creation is potentially expensive; and call reset_coords before-hand. This seems too niche.

Additional context

No response