Create overlay for buble text field suggestions

[bedhub]

Right now the suggestions list from the bubble text field in mail editor changes the content size of the mail editor. This leads to not very nice movement of the content when typing in the mail address. We should make a real overlay for the suggestion list and also refactor the bubble text field input to the new component style.

[vaf-hub]

Test notes have been moved below

[johnbotris]

• In the sharing dialog, the bottom of the overlay will be cut off if it extends past the end. A scrollbar also appears on the dialog which shrinks the width (fixing the first problem should fix the second).
• If the list is scrollable, when using the arrow keys the selection will go out of view, rather than scrolling the list to keep it visible

[johnbotris]

Test notes:

This feature should be tested extensively on different devices and screen sizes. So please take some time :-)

• bubble text field suggestions are shown in a dropdown on top of other content (that should not move around anymore if the number of suggestions changes)
• test all color themes, different screen sizes and devices
• test all places, that the BTF is used: MailEditor (To, Cc and Bcc fields), EditCalendarEvent (add guests), and sharing a calendar
• verify that (height) animation works fine
• verify the height is calculated correctly and it looks ok at the bottom (also if there are many suggestions)
• Using the up and down keys to select in the dropdown will cause the list to scroll to keep the selection in view
• The list will not overflow it's container if too long (check the calendar sharing and template sharing dialogs)

[charlag]

iOS/macOS Safari are also fine. The only thing that doesn't look great is long text cut off horizontally. I think we can fix it later.