feat(install): allow to install hook locally with husky

[GG-HH]

Fixes #1143

Context

Trying to fix error #1143

What has been done

In case the git hooks path is the husky path, add the ggshield command in the husky configuration file

Validation

See issue

PR check list

• As much as possible, the changes include tests (unit and/or functional)
• If the changes affect the end user (new feature, behavior change, bug fix) then the PR has a changelog entry (see doc/dev/getting-started.md). If the changes do not affect the end user, then the skip-changelog label has been added to the PR.

[codecov]

Codecov Report

❌ Patch coverage is 68.75000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.91%. Comparing base (edac2af) to head (4cfbc12).

Files with missing lines	Patch %	Lines
ggshield/cmd/install.py	68.75%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1150      +/-   ##
==========================================
- Coverage   91.97%   91.91%   -0.06%     
==========================================
  Files         144      144              
  Lines        6202     6218      +16     
==========================================
+ Hits         5704     5715      +11     
- Misses        498      503       +5     

Flag	Coverage Δ
unittests	91.91% <68.75%> (-0.06%)	⬇️

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[agateau-gg]

Having both get_local_hook_dir_path() and get_local_hooks_path() is confusing. Maybe name this one get_hooks_path_from_local_git_config() (a bit long, but unambiguous)?

[agateau-gg]

I would expect a functional test to use Husky for real. Is it doable?

I think if you replace the use of run_ggshield() with a call to install_local() then this code can become a unit test for install_local().