Combine Create & See Areas

[Timo21]

The Create Area mode currently starts with an empty map. This could lead to duplicates easily if users don't check the See Areas mode first. Can be discouraged by:

• Showing existing AOIs on the Create Area mode as well, discouraging closely overlapping new ones
• Input validation that checks whether the intersect with any existing AOI is too big and throws some "are you sure" warning

[Timo21]

Also while working on this, input validation could be added to prevent too large bboxes by checking surface area of the defined box

[Timo21]

Discussed during one of our meetings that it could be nice to try and combine See Areas and Create Areas, requiring less clicking radio buttons and naturally discouraging creating new areas where they already exist. I'll change the issue title to reflect that.