Use real types to parse labels

We were using `yaml.Unmarshal` on basic types or inline structs. This
was not efficient and not clear to defined what we expect in labels.
We now use types to unmarshal the labels.

Only the `values` label is, at this time, parsed by GetValuesFromLabel
because this `utils` function is clearly a special case.

generator/labelStructs/doc.go

@@ -0,0 +1,2 @@
+// labelStructs is a package that contains the structs used to represent the labels in the yaml files.
+package labelStructs