Receiver/Station GPS location automated pre-fill for new Receiver Deployments

[xhoenner]

Originally opened by @fjaine in https://github.com/aodn/aatams-content/issues/62.

Some mistakes have been made in the past with GPS locations when creating new Receiver Deployments, mostly due to the following:

• When creating a new Receiver Deployment, the user first selects the Station name
• Based on the Station name selected, the GPS location for this station automatically pre-fills as the Receiver location
• However, the GPS location entered should reflect the precise GPS coordinates of the latest deployment of the receiver for this station, rather than the 'theoretical' station location. If not done properly, this can lead to issues when in the field trying to retrieve receivers using the wrong GPS coordinates...

As such, we suggest that:

• a pop-up message appears when the user selects the station name asking the user "Are these GPS coordinates correct?" (or something of the like...)
  OR
• the GPS coordinate field remains blank (and mandatory) when selecting a station name, thus forcing the user to manually enter the right coordinates