Is your feature request related to a problem?

Narwhals support

Describe the solution you'd like

To be able to run daft.functions.count(mode='all') without having to specify an expression

Describe alternatives you've considered

Getting a column name from a dataframe that the expression gets passed to. But, this is limiting, and makes it harder to write free-standing expressions

In SQL it's easy to write count('*'), and in Polars there's pl.len().

Additional Context

No response

Would you like to implement a fix?

No