ImageGraphic should use tiling if necessarry, get rid of HeatmapGraphic

[kushalkolar]

The only reason HeatmapGraphic exists is to display images with dims larger than the WGPU max texture size (8192, 8192). _ImageTile just adds the chunk index to the pick_info dict but we can instead just use the chunk indices to set the actual index position of events based on the chunk size.

fastplotlib/fastplotlib/graphics/image.py

Lines 323 to 331 in 9a309ef

	def _wgpu_get_pick_info(self, pick_value):
	pick_info = super()._wgpu_get_pick_info(pick_value)
	# add row chunk and col chunk index to pick_info dict
	return {
	**pick_info,
	"row_chunk_index": self.row_chunk_index,
	"col_chunk_index": self.col_chunk_index,
	}