Lights: Rename Spot Size to Beam Angle in UI

This is more consistent with other naming of angles in the user interface,
and more clear.

The identifier has not changed, so no API compatibility is broken.

Fix #144527

Pull Request: https://projects.blender.org/blender/blender/pulls/144661

intern/cycles/blender/addon/ui.py

@@ -1639,7 +1639,7 @@ class CYCLES_LIGHT_PT_beam_shape(CyclesButtonsPanel, Panel):
 
         col = layout.column()
         if light.type == 'SPOT':
-            col.prop(light, "spot_size", text="Spot Size")
+            col.prop(light, "spot_size", text="Angle")
             col.prop(light, "spot_blend", text="Blend", slider=True)
             col.prop(light, "show_cone")
         elif light.type == 'AREA':