feat(core): try to extract repository url from ci env variables

[Paul-GitGuardian]

Following #747, we want CI commands to gather the current repository URL from the CI environment variables first, falling back on git remote -v if variables are not found.

[codecov-commenter]

Codecov Report

Merging #791 (6a26a2c) into main (20d0b01) will increase coverage by 0.22%. Report is 22 commits behind head on main. The diff coverage is 94.38%.

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@@            Coverage Diff             @@
##             main     #791      +/-   ##
==========================================
+ Coverage   91.68%   91.90%   +0.22%     
==========================================
  Files         154      155       +1     
  Lines        6348     6486     +138     
==========================================
+ Hits         5820     5961     +141     
+ Misses        528      525       -3     

Flag	Coverage Δ
unittests	91.90% <94.38%> (+0.22%)	:arrow_up:

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

Files	Coverage Δ
ggshield/cmd/hmsl/hmsl_common_options.py	100.00% <ø> (ø)
ggshield/cmd/iac/scan/all.py	100.00% <ø> (ø)
ggshield/cmd/iac/scan/diff.py	80.76% <ø> (+2.56%)	:arrow_up:
ggshield/cmd/iac/scan/iac_scan_common_options.py	100.00% <100.00%> (ø)
ggshield/cmd/sca/scan/sca_scan_utils.py	87.23% <ø> (+8.51%)	:arrow_up:
ggshield/cmd/secret/scan/ci.py	96.42% <100.00%> (+0.13%)	:arrow_up:
ggshield/cmd/secret/scan/path.py	100.00% <ø> (ø)
ggshield/cmd/secret/scan/precommit.py	100.00% <100.00%> (ø)
ggshield/cmd/secret/scan/prepush.py	100.00% <100.00%> (ø)
ggshield/cmd/secret/scan/prereceive.py	93.54% <100.00%> (+0.10%)	:arrow_up:
... and 9 more

... and 2 files with indirect coverage changes