Improve keyboard actions

[danieldegroot2]

• There's a duplicate highlight for almost all buttons when tabbing to them. (one for the outside element and one for the inside element)
  (Add Event, Login button when adding event, Subscribe, Event Website, Add to Calendar, Edit Event, Repeat Event, not Attend, ...)
• While in the country selector or Kind/Timezone selectors (Add Event)
  -- Pressing tab does not go to the first/next item in the list, in fact it cancels selection.
  -- Pressing Escape does not cancel selection, in fact it confirms selection just like Enter would.
• On the Calendar, (which is semi-known for having small bugs)
• pressing the down button goes to the bottom center date (ie. August 4) instead of the first available date.
  -- We could also use this or up/down to go to the month header. We can already go to the next/previous month with left/right
• When anywhere inside a Sign-up survey, pressing Enter cancels creating a sign-up survey (because it's empty), but Escape again does nothing.

Sidenotes;

• I couldn't check if tabbing works with the link for the list of people attending, but I assume it does..
• On the map for adding location, highlights disappear almost instantly, but it's a known issue that the map doesn't work well.
  -- Initial tab goes nowhere (maybe on the outside element, but it is not visible)
  -- Then there's a highlight for the marker, but I can't seem to find a way to move the marker with the keyboard. I wonder if this is useful at all.
• On Creating a sign-up survey -or a new question-, this enables new buttons, for which needs to be tabbed all the way back to this section. Not sure if this can be done any better.
• If you ever want to log out, noteably, you'll have to do a lot of tabs. (maybe there's already a shortcut for this, idk)

Other tests you can do include Google Lighthouse, W3C checkers or similar online tools (many require registration though).