[FEA] Experiment try to unify implementation of non-nested types and nested types in cudf::contains

[ttnghia]

Currently, cudf::contains implements two separate code paths for non-nested types and nested types. That requires more effort to maintain all of them, comparing to just have one code path that can handle both.

Recently, there was an attempt to use just one code path to handle all data type (ref: #10770 (comment)) in groupby key hashing, which reported no performance regression on basic data types. As such, we should also test and try to unify the two code paths of cudf::contains.

Having just one code path that handles everything, maintenance will be much easier.

[ttnghia]

There was mentioned that the current cudf's customized data structure unordered_multiset is still much faster than cuco::static_map. Since the code path for handling nested types relies on cuco::static_map, we can only address this issue once we can safely switch to using cuco::static_map without much performance regression.

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[vyasr]

The other part of what needs to happen here (in addition to resolving performance regressions caused by differences between cuco::static_map and concurrent_unordered_map) is to introduce the same sort of has_nested templating to the equality comparators as I did for the lexicographic comparator. Then, rather than maintaining a completely separate code path in contains where one uses the old comparator and one uses the new one, we could use the same comparator in both cases.