QMAPS-2129 add startAt / arriveBy options in public transports (draft / poc)

[xem]

• if public transport is enabled, show 3 forms under the direction form (ugly draft, while waiting for final design!)
  

• Pressing "GO" after "start now" updates the URL and computes a route that starts now. (as usual)
  

• Choosing a date/time and pressing "GO" after "start at" updates the URL and computes a route that starts after that date/time
  

• Choosing a date/time and pressing "GO" after "arrive by" updates the URL and computes a route that arrives before that date/time
  

NB: I added the date in the routes summaries. It's a suggestion for Design, to remind people which day the route starts

TODO:

• decide if we want to call the API at any change in the form or after pressing a "ok" submit button (in this PoC it's a button)
• make a select input to choose between the 2 modes (now/start at/arrive by) (here the 3 are displayed)
• decide if we want to replace the native datetime input with a JS calendar date input + a hour selector (here, it's the native one)
• finalize CSS
• Use zustand to handle / remember the values selected ?