Add token authentication

[TimoKramer]

Token authentication in it's basic form works. You can set a token in the configuration and use this token to authenticate against the API. There is the option to use dev-mode which authenticates you always without token. That is good to be used if you don't want to give people the opportunity to run an instance e.g. from the Azure Button.

It might be helpful for future use cases as well to avoid complicated setup when only using locally. To avoid widespread problems in public space dev-mode is not set as default and needs to be activated in the config.

• Closes #16
• adds token authentication
• token can be set via configuration
• dev-mode disables authentication
• automated basic integration tests

[TimoKramer]

should be merged after #1 #14 #15

[TimoKramer]

I would add some more tests to test dev-mode

[TimoKramer]

and an ADR