Resolve "Enable Transmission Request #863fwpt2d #863fwptf5"

Closes #333 (closed)

Only functional solution!

This enables the HCP to request session data and the PAT to fulfill such a request. All the modals on the screen are preliminary and should be reworked. There's going to be another issue for that. For the time being it is only important that things actually work. Looks and user friendliness come at a later point in time 😄

How to test

HCP: click 'Request Patient Data' / 'Gesundheitsdaten anfragen' -> QR-Code

PAT: App to scan the code, should prompt modals

HCP: gets code in an alert

PAT: enter code, pick data to send

HCP: receives data