Store additional user info

[davidotte]

Change Description

Try to be precise. You can additionally add comments to your PR, this might help the reviewer a lot.

This PR adds/changes the following things:

• Ask user for first and last name during registration and send information to the server
• Move to terms and conditions into registration process
• User has to agree to PII, send user agreements to the server

If you used new dependencies: Did you add them to requirements.txt?

no new dep

Who did you ping on Mattermost to review your PR? Please ping that person again whenever you are ready for another review.

@noahho

Breaking changes

If you made any breaking changes, please update the version number.
Breaking changes are totally fine, we just need to make sure to keep the users informed and the server in sync.

Does this PR break the API? If so, what is the corresponding server commit?

Yes, see corresponding PR

Does this PR break the user interface? If so, why?

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[noahho]

Great! Did you check if this will be backwards compatible with old accunts?

[davidotte]

For old accounts the first and last name fields in the user table will just be empty. And we of course do not have any user agreements stored for them.