DRW: Remove DRWTextureFormat in favor or GPUTextureFormat.

Because:
- Less redundancy.
- Better suffixes.

Also a few modification to GPU_texture_create_* to simplify the API:
- make the format explicit to the texture creation process.
- remove the component count as it's specified in the GPUTextureFormat.

source/blender/draw/engines/eevee/eevee_engine.c

@@ -70,7 +70,7 @@ static void eevee_engine_init(void *ved)
 	stl->g_data->valid_double_buffer = (txl->color_double_buffer != NULL);
 
 	/* Main Buffer */
-	DRW_texture_ensure_fullscreen_2D(&txl->color, DRW_TEX_RGBA_16, DRW_TEX_FILTER | DRW_TEX_MIPMAP);
+	DRW_texture_ensure_fullscreen_2D(&txl->color, GPU_RGBA16F, DRW_TEX_FILTER | DRW_TEX_MIPMAP);
 
 	GPU_framebuffer_ensure_config(&fbl->main_fb, {
 		GPU_ATTACHMENT_TEXTURE(dtxl->depth),