Project Creation: Fix max zoom level

[Hagellach37]

for now the maximum zoom level one can use is 19. This should be either adapted to a higher number, or it should be made clear that no higher zoom levels can be displayed.

For projects that use drone imagery zoom level 20 might be still a good choice.

This needs to addressed for:

• mapswipe_workers project creation
• mapswipe_workers check project size
• manager dashboard: set zoom level, max --> xy?
• manager dashboard: validate input geometry size