create confirmation email frontend

[elYanuki]

Change the List so that the teacher can request a confirmation of the rent.

• the signature field should be changed to a button "Bestätigung Anfragen" that should tell the server to send a confirmation mail to the student #39
• When a request was sent the field should be changed to a status display of the confirmation_status of the rent.
  • when the status is declined the field should be clickable and bring up a box that explains that the rent was declined and show the confirmation_message as well as a button "Erneute Bestätigung Anfragen"

Create a page in the frontend that is linked from the mail and allows users to confirm or decline rents

[elYanuki]

• changed tsconfig to compile new ts file
• added simple display of rent to confirm or decline
• changed status display to german

rest fuktioniert sehr gut :)