Add support for Mission Events Frames Kernel

The JUICE will publish mission events frames kernel to store the definitions for mission events (eg. juice_events_crema_5_1_150lb_23_1_v01.tf). Its values will be available in SPICE pool:

   \begindata

      JUICE_MISSION_PHASE_NAME  += ( 'Jupiter_Phase_1' )
      JUICE_MISSION_PHASE_DESC  += ( 'Approach and first ellipse' )
      JUICE_MISSION_PHASE_STRT  += ( '2031-01-19T19:14:21' )
      JUICE_MISSION_PHASE_STOP  += ( '2032-02-08T23:05:31' )

      JUICE_MISSION_PHASE_NAME  += ( 'Jupiter_Phase_2' )
      JUICE_MISSION_PHASE_DESC  += ( 'Energy reduction' )
      JUICE_MISSION_PHASE_STRT  += ( '2032-02-08T23:05:32' )
      JUICE_MISSION_PHASE_STOP  += ( '2032-06-25T12:23:23' )
...
      JUICE_TIMELINE_EVENT_TYPE  += ( 'FLYBY_GANYMEDE' )
      JUICE_TIMELINE_EVENT_NAME  += ( '1G1' )
      JUICE_TIMELINE_EVENT_TIME  += ( '2031-07-21T07:13:28' )

      JUICE_TIMELINE_EVENT_TYPE  += ( 'PERIJOVE' )
      JUICE_TIMELINE_EVENT_NAME  += ( '1PJ' )
      JUICE_TIMELINE_EVENT_TIME  += ( '2031-07-21T20:49:32' )

   \begintext

When present, it would be nice to have a way to pull these values into an EventsDict, eg.:

tour = TourConfig(mk='5_1_150lb_23_1', spacecraft='JUICE', target='Ganymede')

tour.phases
tour.timeline