[mdatagen] use main as package for cmd types (open-telemetry#10130)

This allows us to enabled package test generation for mdatagen itself
(and for telemetrygen in contrib)

Signed-off-by: Alex Boten <223565+codeboten@users.noreply.github.com>

cmd/mdatagen/main.go

@@ -1,6 +1,8 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+//go:generate mdatagen metadata.yaml
+
 package main
 
 import (
@@ -204,6 +206,9 @@ func templatize(tmplFile string, md metadata) *template.Template {
 				"isConnector": func() bool {
 					return md.Status.Class == "connector"
 				},
+				"isCommand": func() bool {
+					return md.Status.Class == "cmd"
+				},
 				"supportsLogs": func() bool {
 					for _, signals := range md.Status.Stability {
 						for _, s := range signals {

cmd/mdatagen/metadata.yaml

@@ -2,5 +2,7 @@ type: mdatagen
 
 status:
   class: cmd
+  stability:
+    alpha: [metrics]
   codeowners:
     active: [dmitryax]

cmd/mdatagen/templates/package_test.go.tmpl

@@ -1,6 +1,6 @@
 // Code generated by mdatagen. DO NOT EDIT.
 
-package {{ .Package }}
+package {{ if isCommand -}}main{{ else }}{{ .Package }}{{- end }}
 
 import (
 	"testing"