fix: check input type for arr/list.contains

[reswqa]

Almost all operations in list/arr namespace ensures the input type when unpack series. But contains is an exception due to the reuse of is_in ops. As a result, you can even call arr.contains on list series.

IMO, we should raise for things like ListSeries.arr.xxx or ArraySeries.list.xxx. After all, they are not essentially the same type. In particular, you can't even convert a list to an array with unequal width.

[mcrumiller]

Should list.contains(array_item) and arr.contains(list_item) be allowed? I kind of think so. Array is a special case of List whereby a property of the lists (their length) is constrainted, but the items themselves can still be considered identical.

I think, though, that we should not allow .arr.contains on series with dtype List. What do others think?

Edit to clarify:

s_list = pl.Series([[1, 2]], dtype=pl.List(pl.Int32))
s_arr = pl.Series([[1, 2]], dtype=pl.Array(pl.Int32, 2))

s_list.list.contains(s_arr)  # should be allowed, and should return [True], as items are identical
s_arr.arr.contains(s_list)   # same

s_list.arr.contains(...)     # should not be allowed, list are too broad to call array methods
s_arr.list.contains(...)     # should be allowed, arrays are specialized lists

[stinodego]

Thanks @reswqa!

Actually, could you add a test for these?

[stinodego]

Actually let met add a test myself real quick, I'm on this PR now anyway!