frontend: map click improvements

[ES-Alexander]

Current behaviour

1. The current icon is a large blob, which gives no meaning and feels imprecise
2. GoTo is the only exposed functionality, but that includes for vehicles that don't support it

Expected or desired behaviour

1. The icon could be replaced with something more intuitive, like mdi-target
2. Functionality should be context dependent
   1. GoTo should ideally only appear for vehicles that support it, and probably only when the vehicle is already armed and in a guided operation mode
   2. Additional relevant functionalities could also be exposed, like those covered in Allow setting GPS(/EKF) origin #1102 and it should be possible to set the Home location manually #1481, and recording/setting landmarks and other points of interest
      • likely best to expose via some kind of radial or dropdown menu

Prerequisites

• I have checked to make sure that a similar request has not already been filed or fixed.