chore: add support for grouping inference in ai commands (scaleway#4919)

Author: remyleone

cmd/scw/testdata/test-main-usage-usage.golden

@@ -3,7 +3,7 @@
 USAGE:
   scw <command>
 
-AVAILABLE COMMANDS:
+AI COMMANDS:
   inference     This API allows you to handle your Managed Inference services
 
 BAREMETAL COMMANDS:

internal/namespaces/inference/v1/custom.go

@@ -5,5 +5,7 @@ import "github.com/scaleway/scaleway-cli/v2/core"
 func GetCommands() *core.Commands {
 	cmds := GetGeneratedCommands()
 
+	cmds.MustFind("inference").Groups = []string{"ai"}
+
 	return cmds
 }