Fix flushdb and flushall

[MeirShpilraien]

Both commands should be broadcasted to all the shards.
In addition, support ssl_password on cluster.

Pull Request check-list

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• 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)?

NOTE: these things are not required to open a PR and can be done
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Description of change

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[codecov-commenter]

Codecov Report

Merging #1926 (1aa301b) into master (9442d34) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1926      +/-   ##
==========================================
+ Coverage   93.02%   93.06%   +0.03%     
==========================================
  Files          76       77       +1     
  Lines       16537    16603      +66     
==========================================
+ Hits        15383    15451      +68     
+ Misses       1154     1152       -2     

Impacted Files	Coverage Δ
redis/cluster.py	92.42% <ø> (ø)
tests/test_cluster.py	98.42% <100.00%> (+<0.01%)	⬆️
redis/commands/json/_util.py	100.00% <0.00%> (ø)
tests/test_commands.py	99.40% <0.00%> (+<0.01%)	⬆️
redis/commands/json/commands.py	89.07% <0.00%> (+0.18%)	⬆️
redis/commands/core.py	90.46% <0.00%> (+0.31%)	⬆️

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