Allow manual input of coordinates for area screenshots

[Anders142536]

Currently the coordinates for the area screenshots are only displayed, but not manually editable. To adjust the coordinates the mouse controls have to be used.

Allow for editing of the coordinates by making the display fields editable. Every edit should immediately update the drawn rectangle. Special handling is required if the user did not draw a rectangle yet but inputs values anyways. These values should also edit the positions of the left and right click so that a modification of the values in the text fields does not cause a new click with left or right click to break.

Discussion on Mod Portal: https://mods.factorio.com/mod/FacAutoScreenshot/discussion/6364ea293cf380827ac4b56d