feat(admin, admin-ui, medusa-js, medusa-react, medusa): Support Admin Extensions (#4761)

Co-authored-by: Rares Stefan <948623+StephixOne@users.noreply.github.com>
Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/admin/src/commands/develop.ts

@@ -0,0 +1,32 @@
+import { AdminOptions, develop as adminDevelop } from "@medusajs/admin-ui"
+import { getPluginPaths, loadConfig } from "../utils"
+
+type DevelopArgs = AdminOptions & {
+  port: number
+}
+
+export default async function develop({ backend, path, port }: DevelopArgs) {
+  const config = loadConfig(true)
+
+  if (!config) {
+    // @medusajs/admin is not part of the projects plugins
+    // so we return early
+    return
+  }
+
+  const plugins = await getPluginPaths()
+
+  await adminDevelop({
+    appDir: process.cwd(),
+    buildDir: config.outDir,
+    plugins,
+    options: {
+      backend: backend || config.backend,
+      path: path || config.path,
+      develop: {
+        port: port || config.develop.port,
+        open: config.develop.open,
+      },
+    },
+  })
+}