Implementation of the BZPOPMAX/BZPOPMIN commands and additional options of ZADD.

[otykhonruk]

What do these changes do?

Implementation of the blocking pop commands for the sorted set: BZPOPMAX and BZPOPMIN.
Implementation of the the CH and INCR options of the ZADD command.

Are there changes in behavior for the user?

Related issue number

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES/ folder
  • name it <issue_id>.<type> (e.g. 588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the PR
  • ensure type is one of the following:
    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example:
    Fix issue with non-ascii contents in doctest text files.

[codecov]

Codecov Report

Merging #618 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #618      +/-   ##
==========================================
- Coverage   96.85%   96.85%   -0.01%     
==========================================
  Files          57       57              
  Lines        8482     8540      +58     
  Branches      571      578       +7     
==========================================
+ Hits         8215     8271      +56     
- Misses        191      192       +1     
- Partials       76       77       +1

Impacted Files	Coverage Δ
aioredis/commands/sorted_set.py	100% <100%> (ø)	⬆️
tests/sorted_set_commands_test.py	100% <100%> (ø)	⬆️
tests/_testutils.py	84.21% <0%> (-3.51%)	⬇️

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[popravich]

Please fulfill last two points of checklist

[otykhonruk]

Please fulfill last two points of checklist

@popravich Done.

[popravich]

Thanks