move cli-plugins metadata types/consts to a separate package

This prevents cli-plugins having to import the plugin-manager.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

e2e/cli-plugins/plugins/badmeta/main.go

@@ -7,11 +7,11 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/docker/cli/cli-plugins/manager"
+	"github.com/docker/cli/cli-plugins/metadata"
 )
 
 func main() {
-	if len(os.Args) == 2 && os.Args[1] == manager.MetadataSubcommandName {
+	if len(os.Args) == 2 && os.Args[1] == metadata.MetadataSubcommandName {
 		fmt.Println(`{invalid-json}`)
 		os.Exit(0)
 	}

e2e/cli-plugins/plugins/nopersistentprerun/main.go

@@ -3,7 +3,7 @@ package main
 import (
 	"fmt"
 
-	"github.com/docker/cli/cli-plugins/manager"
+	"github.com/docker/cli/cli-plugins/metadata"
 	"github.com/docker/cli/cli-plugins/plugin"
 	"github.com/docker/cli/cli/command"
 	"github.com/spf13/cobra"
@@ -26,7 +26,7 @@ func main() {
 			},
 		}
 	},
-		manager.Metadata{
+		metadata.Metadata{
 			SchemaVersion: "0.1.0",
 			Vendor:        "Docker Inc.",
 			Version:       "testing",

e2e/cli-plugins/plugins/presocket/main.go

@@ -7,14 +7,14 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/docker/cli/cli-plugins/manager"
+	"github.com/docker/cli/cli-plugins/metadata"
 	"github.com/docker/cli/cli-plugins/plugin"
 	"github.com/docker/cli/cli/command"
 	"github.com/spf13/cobra"
 )
 
 func main() {
-	plugin.Run(RootCmd, manager.Metadata{
+	plugin.Run(RootCmd, metadata.Metadata{
 		SchemaVersion: "0.1.0",
 		Vendor:        "Docker Inc.",
 		Version:       "test",