• Update the header to say "Calendars"
• Remove the "add calendar" button from calendar list header
• The navigation chevron should be where the "add calendar" button was
• Hover should affect the whole header (full with of the sidebar) and have the bg color as gray 20
• Animation of opening and closing (use reduced motion:no-preferences)
• Have a spacer so that the bottom buttons dont come all the way up when calendar is collapsed

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/51db5bd34c2a
Update calendar list header in calendar side panel area. r=aleca

This broke browser_interactionTelemetry.js and browser_calDAV_discovery.js. They both want to click on the old .calendar-list-create button. We should update those tests to use the new button. There might also be other tests that try to create calendars with that button (that aren't currently failing due to the existing failures).

Example failures:
https://treeherder.mozilla.org/logviewer?job_id=404046301&repo=comm-central&lineNumber=3178
https://treeherder.mozilla.org/logviewer?job_id=404046319&repo=comm-central&lineNumber=2064

Edit:
also browser_calendarList.js

Let's backout this and fix the tests.
Thanks for spotting the issues.

Backout changesets for causing test failures: https://hg.mozilla.org/comm-central/rev/bc9c23741b06cee6e9d8b0645f1bfd1683c283c7

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/5e85bd095d32
Update calendar list header in calendar side panel area. r=aleca