Saving a site without changing the geometry via the edit page will blank out the area

[chrisala]

To reproduce:

1. Create a site in MERIT.
2. View the site, note the area.
3. Edit the site, change the name or external Id only.
4. Save the site.

Expected:
The name/external id is updated as edited with no other changes.

Actual:
The area is removed.

[temi]

Another ticket this bug is impacting - https://support.ehelp.edu.au/a/tickets/253841.

There are sites which are MultiLine. The interface does not provide a way to draw them. Hence we might need a method to populate the value via another method.