DXCDT-519: Improve DX for managing is_token_endpoint_ip_header_trusted on auth0_client resource

[sergiught]

🔧 Changes

At the moment we only allow managing the is_token_endpoint_ip_header_trusted property of the client when the resource gets updated; on create it gets skipped. This unfortunately requires 2 terraform applies in combination with an auth0_client_credentials resource.

To avoid having to run 2 terraform applies, on create if the is_token_endpoint_ip_header_trusted is set, we default the authentication method (token_endpoint_auth_method) of the client to client_secret_post.

📚 References

• Document how to use is_token_endpoint_ip_header_trusted #620

🔬 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 #796 (6ac4399) into v1 (308cc6a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##               v1     #796      +/-   ##
==========================================
+ Coverage   90.43%   90.44%   +0.01%     
==========================================
  Files          99       99              
  Lines       13189    13193       +4     
==========================================
+ Hits        11928    11933       +5     
  Misses        893      893              
+ Partials      368      367       -1     

Files Changed	Coverage Δ
internal/auth0/client/expand.go	91.76% <100.00%> (+0.01%)	⬆️
internal/auth0/client/resource.go	98.84% <100.00%> (+<0.01%)	⬆️

... and 1 file with indirect coverage changes