[Feature Request] MSAL Python supports Prompt.Create so that customers can implement self-service sign-up

[henrik-me]

Note: MSAL.NET work item, was completed and can be used as reference implementation.

Is your feature request related to a problem? Please describe.
When developers want to implement self-service sign up for their apps, they can use a prompt=create, triggered by a "Sign-up" link in their app. The end user can then enter the 'create account' experience.

Describe the solution you'd like
MSAL.NET should propose a new property named Create in the Prompt class. When using this property, MSAL.NET would send 'prompt=create' to the authorize endpoint, which will trigger the sign-up experience.

Additional context

Example URL:
https://login.microsoftonline.com/d014fd44-d398-4813-a3a9-8cd725f7f356/oauth2/authorize?
client_id=da53de5a-636b-425f-ad57-0f62d6f974c7
&response_type=id_token
&resource=da53de5a-636b-425f-ad57-0f62d6f974c7
&scope=openid
&nonce=default_nonce
&redirect_uri=https://jwt.ms
&prompt=create

The draft OIDC spec for this is here: https://openid.net/specs/openid-connect-prompt-create-1_0.html

Work to do

• Expose a new Create property in Prompt.
• Wire-up the prompt so that 'prompt=create' is sent to the authorize endpoint when this prompt is used.
• Update the wiki page, or better redirect it to the docs.ms page, which would, however need to be synced
  Update after release
• Update the docs.ms AcquireToken desktop scenario page.
  MS Docs PR Merge after release

[rayluo]

Work to do

• Expose a new Create property in Prompt. Automatically supported in acquire_token_interactive etc..
• Wire-up the prompt so that 'prompt=create' is sent to the authorize endpoint when this prompt is used. See above.
• Update the wiki page, or better redirect it to the docs.ms page, which would, however need to be synced
  Update after release Adding one more line into the existing interactive flow sample. (PR A demo on how to use prompt=create #360)
• Update the docs.ms AcquireToken desktop scenario page. This new MS Docs PR is waiting for someone to review.