DXCDT-741 Add support for configuring email provider

[acwest]

Auth0 provides integration capabilities with many email providers like sendgrid, mailgun, mandrill etc.
As an extension to this, it now also supports Custom Email Provider which is tied to an action.

🔧 Changes

Add auth0 email provider commands:

• auth0 email provider show
• auth0 email provider create
• auth0 email provider update
• auth0 email provider delete

📚 References

• https://auth0.com/docs/api/management/v2/emails/post-provider
• https://auth0.com/docs/api/management/v2/emails/patch-provider
• https://auth0.com/docs/api/management/v2/emails/get-provider
• https://auth0.com/docs/api/management/v2/emails/delete-provider

🔬 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

Attention: Patch coverage is 65.39510% with 127 lines in your changes missing coverage. Please review.

Project coverage is 70.30%. Comparing base (da13038) to head (909a37e).

Files with missing lines	Patch %	Lines
internal/cli/email_provider.go	66.90%	72 Missing and 20 partials ⚠️
internal/display/email_provider.go	60.22%	27 Missing and 8 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1121      +/-   ##
==========================================
- Coverage   70.38%   70.30%   -0.08%     
==========================================
  Files          94       96       +2     
  Lines       13284    13651     +367     
==========================================
+ Hits         9350     9598     +248     
- Misses       3388     3479      +91     
- Partials      546      574      +28     

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