Add json field to PhoneDevice model

[NewGlad]

Description

JSON field to PhoneDevice model to have an ability to store arbitary data

Motivation and Context

In my project in addition to the existing field declared in the PhoneDevice model, I also want to store some additional data, such as request id, timestamp of last sms sent, and some more I think that it is a very common desire, so looks like it is very convenient to have some field with arbitrary structure to have a way to store some additional data in the standard model

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

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

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[moggers87]

Not sure I see the need for this in django-two-factor-auth. You can get the same effect by using Django's multi table inheritance i.e. subclass PhoneDevice and use your subclass when you want to access the additional fields.

Closing this PR as it's over 6 months old, feel free to comment if you disagree :smiley_cat: