chore: Add SonarCloud config

[slarse]

Carbon copy of #464, but the head is in the SpoonLabs/Sorald repo instead of my personal fork.

[codecov]

Codecov Report

Merging #465 (42db532) into master (1bfe693) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #465   +/-   ##
=========================================
  Coverage     89.49%   89.49%           
  Complexity      541      541           
=========================================
  Files            66       66           
  Lines          1819     1819           
  Branches        148      148           
=========================================
  Hits           1628     1628           
  Misses          117      117           
  Partials         74       74           

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[monperrus]

Per our conversation, we want to merge this but we don't want comment to posted, we want only the Github PR status check.

[sonarqubecloud]

SonarCloud Quality Gate failed.

5 Bugs
0 Vulnerabilities
7 Security Hotspots
299 Code Smells

88.3% Coverage
0.0% Duplication

[slarse]

Test failures probably due to GHA backend trouble: https://www.githubstatus.com/incidents/cj7gzzj30411

[slarse]

@monperrus This is now ready for merge.

I've disabled PR comments in the SonarCloud UI, so we'll see if it honors that.

Note that the PR status check will not be posted on PRs that originate from forks, due to the security implications we discussed earlier. This seems to be something of an unsolved problem for SonarCloud, see e.g. this SO post and the fact that the Travis plugin has it as an upcoming feature.

We can work around that by our members working within the repository instead of on private forks, but external contributors won't have their code vetted by SonarCloud.

[fermadeiral]

LGTM.

[slarse]

@fermadeiral feel free to merge!

[fermadeiral]

Ok! Thank you, @slarse!

[monperrus]

great milestone, thanks!