Switch ui/graphviz to overlay convention

.orchestra/config/components.yml

 #@ load("@ytt:template", "template")
 #@ load("@ytt:data", "data")
 
-#@ load("/components/ui/graphviz.lib.yml", "graphviz_component")
 #@ load("/components/ui/adaptagrams.lib.yml", "adaptagrams_component")
 #@ load("/components/ui/cold_revng.lib.yml", "cold_revng_component")
 #@ load("/components/ui/mesa.lib.yml", "mesa_component")
@@ -22,7 +21,6 @@
 
 #@ load("/global_options.lib.yml", "options")
 components:
-  ui/graphviz: #@ graphviz_component
   ui/adaptagrams: #@ adaptagrams_component
   ui/cold-revng: #@ cold_revng_component
   ui/mesa: #@ mesa_component

.orchestra/config/components/ui/graphviz.lib.yml → .orchestra/config/components/ui/graphviz.yml

+#@ load("@ytt:overlay", "overlay")
 #@ load("/lib/create_component.lib.yml", "single_build_component")
 
 #@ load("/global_options.lib.yml", "options")
@@ -75,6 +76,8 @@ dependencies:
   - libltdl
 #@ end
 
+#@overlay/match by=overlay.all, expects=1
+#@overlay/match-child-defaults missing_ok=True
 ---
-#@ graphviz_component = single_build_component(**_graphviz_args())
-
+components:
+  ui/graphviz: #@ single_build_component(**_libunwind_args())