## What changes were proposed in this pull request?
This introduces a new SQL function 'xxhash64' for getting a 64-bit hash of an arbitrary number of columns.
This is designed to exactly mimic the 32-bit `hash`, which uses
MurmurHash3. The name is designed to be more future-proof than the
'hash', by indicating the exact algorithm used, similar to md5 and the
sha hashes.
## How was this patch tested?
The tests for the existing `hash` function were duplicated to run with `xxhash64`.
Closes#24019 from huonw/hash64.
Authored-by: Huon Wilson <Huon.Wilson@data61.csiro.au>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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