🔥(tokens) remove colors sub maps

Create color sub maps seems to be a good idea but in fact was not. In
fact if with need to create token sub map this structure should appear
within the tokens module.

.changeset/many-taxis-promise.md

@@ -0,0 +1,5 @@
+---
+"@openfun/cunningham-tokens": minor
+---
+
+Do not generate sass sub maps