Pairwise subpackage

[SkafteNicki]

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

We already have a pairwise module in functional with a single function embedding_similarity. This PR expands with multiple new metrics (that also deprecates the embedding_similarity) so we have something that are much more similar to sklearns
pairwise metrics:
https://scikit-learn.org/stable/modules/metrics.html#metrics

Currently implements:

• Cosine similarity
• Linear similarity
• euclidean distance
• manhatten distance

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

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[codecov]

Codecov Report

Merging #553 (51b81b4) into master (8bbc750) will increase coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #553   +/-   ##
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  Coverage      95%    95%           
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  Files         136    142    +6     
  Lines        4926   5004   +78     
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+ Hits         4681   4759   +78     
  Misses        245    245