feat: custom payload properties for registration

[luke-z]

PR to implement the feature proposed in issue #189.

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

Added the possibility to add custom user fields to the registration payload.

[field: string]: string | number | boolean | object | Array<string | number | boolean | object>

The types string, number, boolean and object together with the same types as an array should cover all possible fields in Strapi.

I also checked if the register endpoint can somehow handle FormData (spoiler, it doesn't) to add a profile picture on registration. But since this would be a custom change to a Strapi controller, it's not really needed here.

Furthermore I added the cas authentication provider which I found in this tablist and the possibility to add a custom provider string, as it is possible to add custom providers to Strapi.

Finally, I went through all pages of the documentation and just verified / corrected links which point to a certain line of code. I also corrected the register example which used identifier & password as payload properties and added the phoneNumber property as an example.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes (if not applicable, please state why)

[benjamincanac]

I completely forgot about updating the links in the documentation after all the changes we made recently.
Thank you so much @luke-z!!