bug: incorrect mapping of `*strip` to `*trim`

[ingomueller-net]

What happened?

Ibis' strip, lstrip, and rstrip take no additional arguments and remove whitespace; Substrait's trim, ltrim, and rtrim, however, do take an additional argument, which specifies the characters that should be removed. Currently, *strip is mapped to *trim as is, leading to an exception because to signature of the form ('str',) is found for *trim. Instead, we should map to a call to *trim that builds a character set of whitespace characters.

Example:

def trim_expr(nation):
    new_col = nation.n_name.strip().name("trim_N_NAME")
    return nation[nation.n_name, new_col]

What version of ibis-substrait are you using?

ibis-framework==9.5.0
ibis-substrait==4.0.1

What substrait consumer(s) are you using, if any?

No response

Relevant log output

ValueError: No matching extension type found for function ltrim with input types ('str',)