DXCDT-147: Add new auth0_client_credentials resource with support for JWT CA

[sergiught]

🔧 Changes

In this PR we are adding a dedicated auth0_client_credentials resource to manage all things credentials of an auth0_client resource, e.g. authentication method, client secret and client credentials.

📚 References

🔬 Testing

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

[codecov-commenter]

Codecov Report

Merging #588 (614f3a1) into bump/go-auth0 (abe01d2) will decrease coverage by 0.38%.
The diff coverage is 78.02%.

Additional details and impacted files

@@                Coverage Diff                @@
##           bump/go-auth0     #588      +/-   ##
=================================================
- Coverage          87.24%   86.86%   -0.38%     
=================================================
  Files                 70       71       +1     
  Lines              10693    11148     +455     
=================================================
+ Hits                9329     9684     +355     
- Misses              1037     1116      +79     
- Partials             327      348      +21     

Impacted Files	Coverage Δ
internal/provider/provider.go	100.00% <ø> (ø)
internal/auth0/client/resource_credentials.go	77.77% <77.77%> (ø)
internal/auth0/client/resource.go	97.21% <100.00%> (+0.01%)	⬆️