feat: add --format json support to ps:scale

The `ps:scale` command now accepts a `--format` flag that defaults to `stdout` and can be set to `json` to emit the current formation as a JSON array of process type and quantity objects, matching the JSON output the `:report` subcommands already provide. The flag only applies when displaying the current formation; it is ignored when process types are supplied for scaling. When no scale has been set for the app, the JSON output is an empty array.

plugins/ps/functions.go

@@ -1,6 +1,7 @@
 package ps
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
@@ -243,12 +244,22 @@ func restorePrep() error {
 	return nil
 }
 
-func scaleReport(appName string) error {
+func scaleReport(appName string, format string) error {
 	formations, err := getFormations(appName)
 	if err != nil {
 		return err
 	}
 
+	if format == "json" {
+		out, err := json.Marshal(formations)
+		if err != nil {
+			return err
+		}
+
+		common.Log(string(out))
+		return nil
+	}
+
 	common.LogInfo1Quiet(fmt.Sprintf("Scaling for %s", appName))
 
 	content := []string{}