Added explicit check for handling missing env variables for login

[duedares-rvj]

Moved checking required env variables from ConfigureContextFunc to when the provider actually get configured in ConfigureProvider during the planning step.

This allows picking variable which might be declared in the tf file itself

provider "auth0" {
  domain        = "<domain>"
  client_id     = "<client-id>"
  client_secret = "<client-secret>"
  debug         = "<debug>"
}

The above is not recommended and use of env variables is advised.

🔧 Changes

📚 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

All modified and coverable lines are covered by tests ✅

Project coverage is 89.35%. Comparing base (152ca2d) to head (db7685a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1065      +/-   ##
==========================================
+ Coverage   89.27%   89.35%   +0.08%     
==========================================
  Files         126      126              
  Lines       17487    17481       -6     
==========================================
+ Hits        15612    15621       +9     
+ Misses       1335     1320      -15     
  Partials      540      540              

Files with missing lines	Coverage Δ
internal/config/config.go	95.52% <100.00%> (-2.06%)	⬇️
internal/provider/provider.go	100.00% <100.00%> (+24.32%)	⬆️