Add support for CLUSTER LINKS

[dvora-h]

Pull Request check-list

Please make sure to review and check all of these items:

• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to CHANGES file?

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Description of change

closes #1945

[codecov-commenter]

Codecov Report

Merging #2019 (0f8bd85) into master (98fd06e) will decrease coverage by 0.94%.
The diff coverage is 27.27%.

@@            Coverage Diff             @@
##           master    #2019      +/-   ##
==========================================
- Coverage   92.64%   91.69%   -0.95%     
==========================================
  Files         100      100              
  Lines       20953    20211     -742     
==========================================
- Hits        19411    18532     -879     
- Misses       1542     1679     +137     

Impacted Files	Coverage Δ
tests/test_cluster.py	97.46% <11.11%> (-0.96%)	⬇️
redis/commands/cluster.py	94.11% <100.00%> (-0.76%)	⬇️
tests/test_function.py	21.51% <0.00%> (-78.49%)	⬇️
tests/test_ssl.py	40.80% <0.00%> (-6.22%)	⬇️
redis/__init__.py	85.71% <0.00%> (-4.77%)	⬇️
redis/retry.py	95.83% <0.00%> (-4.17%)	⬇️
redis/asyncio/retry.py	92.30% <0.00%> (-3.85%)	⬇️
tests/test_graph_utils/test_edge.py	93.93% <0.00%> (-3.36%)	⬇️
tests/conftest.py	86.97% <0.00%> (-2.63%)	⬇️
tests/test_graph.py	88.30% <0.00%> (-2.33%)	⬇️
... and 50 more

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