Feature: Add/extend console commands to enable screenshot automation (#9771)
* Add: `zoomto` console command for main viewport
Similar in spirit to `scrollto`, `zoomto` takes an absolute zoom level
from the user and sets the main viewport to that level while respecting
both the absolute minimum and maximum zoom levels supported by the game
and any limitations imposed by the local client settings.
* Add: optional `instant` flag for `scrollto` command
Using this flag has two effects:
- if the user has smooth scrolling enabled, the scroll action will take
place as if it were not enabled
- the viewport is redrawn immediately, so any successive `screenshot`
command will actually work correctly
The original positional arguments are processed like same before.