Improve minhash performance by using more working memory

[davidwendt]

Description

Experimental performance improvement that removes the atomic calls by creating a large working memory to hold intermediate hashes that are then reduced to the output.
The working memory is approximately = (number of input rows x number of seeds x 32) x (size-of hash-type) bytes.
The size-of hash-type would be either 4 bytes (32-bit hash version) or 8 bytes (64-bit hash version).

Checklist

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