Improve usability of dynamic location actions

Description

• When a user visits the location tab of a configuration it could be possible that the button Start Dynamic Location is disabled.
• The reasons the button is disabled are:
  • no device with a measured quantity is mounted
  • for the selected Configuration at Date a device with measured quantity is not mounted

So the user must know when a particular device with the desired measured quantity is mounted.

That behavior is not intuitive and the user must remember too much.

Suggestion

• the button Start Dynamic Location should always be enabled
  • Discussion: Also if there were no device mounts with measured quantities?
    • NO: Just ignore time restricitions
• The form to start a new dynamic location action should be updated
  • the devices (with the desired measured quantity) that measure x,y (and optional z) should be selected first
  • afterwards the start date must be selected
  • selecting end date can be optional if the selected devices are mounted without end date, otherwise it must be provided