Update xxhash_64 to utilize the cuco equivalent implementation

[PointKernel]

Description

This PR updates xxhash_64 to leverage the cuco equivalent implementation and makes it available as a cudf detail utility, as requested by @mhaseeb123. Additionally, it fixes a minor issue in the murmurhash3_x64_128.cuh header by adding the missing #pragma once directive.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[mhaseeb123]

Thanks for quickly adding these changes.

[PointKernel]

/merge