Appointments: eMail Sender/'From' Field is misleading - should use 'Reply to'

Is your feature request related to a problem? Please describe.

Currently, there are four different e-mails sent from the server:

1. verification of the booker e-mail address
2. confirmation of the booking to the booker
3. confirmation of the booking to the organizer
4. cancelation / date change to the booker

All three e-mails have the problem that the sender/From: field is misleading, because the name of a person is combined with the e-mail address of the server:

1. From: Organizer Name <noreply@yourserver.org>
2. From: Organizer Name <noreply@yourserver.org>
3. From: Booker Name <noreply@yourserver.org>
4. Form: Organizer Name via Nextcloud instance Name <noreply@yourserver.org>

This causes problems like

• server address getting flagged as spam
• replies that end up going to the noreply address of the server or
• false address association inside mail clients. For example my Apple Mail suggests me now to wite e-mails to a client (that once used the appointment booking) via noreply@ourserver.org.

Describe the solution you'd like

We should use the name of the Nextcloud instance in the From: field and add a Reply to: field with the name and matching e-mail address of the person:

1. From: Nextcloud Instance Name <noreply@yourserver.org>, Reply to: Organizer Name <organizer@mail.org>
2. From: Nextcloud Instance Name <noreply@yourserver.org>, Reply to: Organizer Name <organizer@mail.org>
3. From: Nextcloud Instance Name <noreply@yourserver.org>, Reply to: Booker Name <booker@sample.com>
4. From: Nextcloud Instance Name <noreply@yourserver.org>, Reply to: Organizer Name <organizer@mail.org>

Describe alternatives you've considered

No response

Additional context

We should then also remove the sentence in the bottom of the e-mails, saying Please don't anser to this e-mail.