Add STATIC_CALLED_ON_INSTANCE warning

[clayjohn]

@akien and I discussed this in the PR review meeting this morning. This warns users when they call static functions from objects instead of calling them from the class.

The purpose of this warning is to avoid the silent failure resulting from functions which have become static recently (e.g. #67319).

Now users will have a warning hinting that they may need to change their code.

The following code:

func _ready():
	var img = Image.new()
	img.create(4, 4, false, Image.FORMAT_RGBA8)
	var imgtex = ImageTexture.new()
	imgtex.create_from_image(img)

Results in this warning

Once this PR and #67361 are merged, we should be able to move forward with making some other functions static as in #63332

[akien-mga]

Thanks!