Add options to reduce lightmaps disk usage.

Added BakedLightmap.use_hdr and BakedLightmap.use_color properties
that can reduce the flie size of lightmap texture at the expense of quality.

Changed the denoiser to work in a single buffer, reducing RAM
usage. Also added the `-mstackrealign` flag in the denoiser compilation
for MinGW builds. This flag helped fix a bug in Embree, so I want to see
if it will help fix GH #45296.

doc/classes/BakedLightmapData.xml

@@ -23,6 +23,12 @@
 			<description>
 			</description>
 		</method>
+		<method name="clear_data">
+			<return type="void">
+			</return>
+			<description>
+			</description>
+		</method>
 		<method name="clear_users">
 			<return type="void">
 			</return>