return metadata in the response headers

[vincentsarago]

titiler/src/titiler/core/titiler/core/factory.py

Lines 968 to 975 in 1825dce

	content, media_type = render_image(
	image,
	output_format=format,
	colormap=colormap or dst_colormap,
	**render_params.as_dict(),
	)
	return Response(content, media_type=media_type)

It could be useful for the client application to get metadata from the response, in some endpoints:

• /preview - bounding box, image min/max, crs (might be tricky but we can restrict to epsg number)
• /tiles - image min/max

for mosaic we already have an optional x_assets header, we could add x_assets_number...

titiler/src/titiler/mosaic/titiler/mosaic/factory.py

Lines 371 to 373 in 1825dce

	headers: Dict[str, str] = {}
	if OptionalHeader.x_assets in self.optional_headers:
	headers["X-Assets"] = ",".join(assets)