[FEA] Support polars.Expr.str.strip_suffix in cudf-polars

[brandon-b-miller]

Is your feature request related to a problem? Please describe.
Today on branch-25.08, we lack support for polars.Expr.str.strip_suffix. Running the example from the docs yields:

import polars as pl
engine = pl.GPUEngine(raise_on_fail=True)

df = pl.DataFrame({"a": ["foobar", "foobarbar", "foo", "bar"]}).lazy()
df = df.with_columns(pl.col("a").str.strip_suffix("bar").alias("stripped"))
res = df.collect(engine=engine)
print(res)

 NotImplementedError: String function <Name.StripSuffix: 37>

Describe the solution you'd like
I'd like the above code to be able to execute using the polars GPU backend. This is slightly different than what is offered by cudf::strings::strip in that it will only strip the provided characters if they appear in the passed order. As such there doesn't appear to be a direct libcudf equivalent today.

Describe alternatives you've considered
N/A

Additional context
#16480