[FEA] Support polars.Expr.str.json_path_match 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.json_path_match. Running the example from the docs yields:

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

df = pl.DataFrame(
    {"json_val": ['{"a":"1"}', None, '{"a":2}', '{"a":2.1}', '{"a":true}']}
).lazy()

df = df.with_columns(matched=pl.col("json_val").str.json_path_match("$.a"))

res = df.collect(engine=engine)
print(res)

 NotImplementedError: String function <Name.JsonPathMatch: 18>'

Describe the solution you'd like
I'd like the above code to be able to execute using the polars GPU backend. Like other JSON related features, libcudf contains some of the building blocks for eventually supporting this, though I don't see an obvious 1-1 API this can map to in the immediate term.

Describe alternatives you've considered
N/A

Additional context
#16480