Calendar event location autocompletion delivering problematic multi-line locations

[brad2014]

When entering the event location of a calendar event, the address taken from contact autocompletion is translated to a multi-line format, which is problematic in a few ways:

1. The event location input field doesn't expand to display the multi-line location when it is stuffed, so the autocompleted address is invisible until the user types in the field (causing it to resize).
2. Other applications (Thunderbird, Google Calendar), more or less expect locations in VCAL and ICS files (e.g. attached to meeting invitations) to be on a single line. Thunderbird, for example, renders multiline locations by concatenating the lines: "123 High StreetSan FranciscoCA94114US". Ugly!

Steps to reproduce

1. In the calendar window, enter a new event
2. In the event location field, type in the name of a contact who has an address, and select the contact
3. Notice the address isn't fully visible (the field is only one line high, but the address is multiline), and when the iMip message is sent, notice it has a multi-line location that will choke other mail clients.

Expected behaviour

1. Instead of rendering the address as
   123 High Street
   San Francisco
   CA
   94114
   US

Translate it to:
123 High Street, San Francisco, CA, 94114, US

(Aside: this address format is suitable for pasting into mapping services, like openstreetmap or google maps. If only the iMip email had a link to pull up the map...)
(Aside: roundcube has a configuration variable that controls the order of address fields, allowing the postal code to come in the right place for the users locale - does nextcloud).

[nextcloud-bot]

GitMate.io thinks possibly related issues are #4880 (Calendars invitations for event in shared calendars), #3044 ([WIP] Calendar events email reminders), #3830 (No calendar invitation send for event in shared calendars ), #10864 (Automatically delete old calendar events), and #3014 (Calendar event invitation automatically creates a new 'personal' calendar).

[brad2014]

Moved to issue nextcloud/calendar#933