Add support for labels on automation functions

Idea for these labels is to give instructions which labels to copy
on step and on workflow when function step is added to the graph.

Labels are defined with "step,workflow", "workflow" or "step" for value.
UI should follow these instructions when copying labels to workflow
and/or step.

pkg/codegen/afunc.go

@@ -32,6 +32,7 @@ type (
 	aFuncDef struct {
 		Name    string
 		Kind    string
+		Labels  map[string]string
 		Meta    *aFuncMetaDef
 		Params  aFuncParamSet
 		Results aFuncResultSet

pkg/codegen/assets/afunc.gen.go.tpl

@@ -92,6 +92,7 @@ func (h {{ $.Name }}Handler) {{ export .Name }}() *atypes.Function {
 	return &atypes.Function{
 		Ref: {{ printf "%q" ( $REF ) }},
 		Kind: {{ printf "%q" .Kind }},
+		Labels: {{ printf "%#v" .Labels }},
 		{{- if .Meta }}
 		Meta: &atypes.FunctionMeta{
 			{{- if .Meta.Short }}