implement REDQ based on original contribution by @Jimenius

[nuance1979]

• I have marked all applicable categories:
  • exception-raising fix
  • algorithm implementation fix
  • documentation modification
  • new feature
• I have reformatted the code using make format (required)
• I have checked the code using make commit-checks (required)
• If applicable, I have mentioned the relevant/related issue(s)
• If applicable, I have listed every items in this Pull Request below

Following discussion in #514, I take the REDQ code out and submit them as an independent PR. Most credit goes to @Jimenius .

[codecov-commenter]

Codecov Report

Merging #623 (d25da3b) into master (41afc25) will increase coverage by 0.02%.
The diff coverage is 87.69%.

@@            Coverage Diff             @@
##           master     #623      +/-   ##
==========================================
+ Coverage   93.54%   93.56%   +0.02%     
==========================================
  Files          67       68       +1     
  Lines        4433     4556     +123     
==========================================
+ Hits         4147     4263     +116     
- Misses        286      293       +7     

Flag	Coverage Δ
unittests	93.56% <87.69%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
tianshou/policy/modelfree/redq.py	84.84% <84.84%> (ø)
tianshou/utils/net/common.py	92.18% <95.65%> (+0.52%)	⬆️
tianshou/env/pettingzoo_env.py	91.48% <100.00%> (+0.58%)	⬆️
tianshou/policy/__init__.py	100.00% <100.00%> (ø)
tianshou/utils/net/continuous.py	97.91% <100.00%> (ø)
tianshou/policy/base.py	80.89% <0.00%> (+5.73%)	⬆️

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