ci: add a github bot to support advanced PR review workflows

[aeddi]

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.29%. Comparing base (534e652) to head (4a3e93d).
Report is 11 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3037      +/-   ##
==========================================
- Coverage   63.38%   63.29%   -0.10%     
==========================================
  Files         566      548      -18     
  Lines       79490    78810     -680     
==========================================
- Hits        50381    49879     -502     
+ Misses      25717    25564     -153     
+ Partials     3392     3367      -25     

Flag	Coverage Δ
contribs/gnodev	60.57% <ø> (ø)
contribs/gnofaucet	14.82% <ø> (ø)
gno.land	67.18% <ø> (-0.20%)	⬇️
gnovm	67.88% <ø> (+<0.01%)	⬆️
misc/genstd	79.72% <ø> (ø)
tm2	62.39% <ø> (-0.04%)	⬇️

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[thehowl]

@aeddi would you like a preliminary review?

[ltzmaxwell]

could you please add a brief description to give people an early preview, even if it's draft?