Change log-in flow for study

[tamslo]

• Log in on app start
• Remove onoboarding
• User needs to change password before using app
• Download data with same credentials
• Username, password plus firstname, lastname, … [additional factors to make it more secure] (@tamslo ask Matteo)

Keycloak resources to update passwords

• send users link to have them initialize their password themselves
• ask users to change password on first log in
• idea to require providing additional information: "encode in user name", e.g. have them use their full name as a user name instead of their email address