TileMapEditor Fix preview rendering and transform calculations

[kleonc]

• Makes the preview tile rects be properly transformed. Previously the transform was applied to the tile rect before sending the draw command to the rendering server. Doing so resulted in obtaining the AABB (here box = rect) of the actual potentially not axis aligned rect, and that's what was send to be drawn. Now an untransformed local tile rect is send, and its transform is applied on top of the canvas item used for drawing on the rendering server.

Example for a skewed TileMap:

Before	After

Fixes #74969.

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• Makes the calculations for input/rendering include the canvas transform the given TileMap is in.

Example for a TileMap in rotated and scaled CanvasLayer:

Before	After

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• Makes grid fading be properly calculated for selections of more than one tile:

Before	After

[YuriSizov]

Thanks!

[YuriSizov]

Cherry-picked for 4.0.2.