fix: prefixed plugin package name (#4811)

Summary:
When distributing plugin over Marketplace. Currently there is an issue with downloading a plugin to `tmp` folder if the plugin `packageName` starts with `company-prefix/flipper-plugin-name`. It would throw `ENONET` error while trying to stream the response data into `tmp` folder.

## Changelog

- add support for prefixed plugin package names (`shopify/flipper-plugin-name`,...)

Pull Request resolved: https://github.com/facebook/flipper/pull/4811

Test Plan: - Try install a plugin from Marketplace which has `/` in the plugin `package.json` `name`.

Reviewed By: lblasa

Differential Revision: D46679195

Pulled By: passy

fbshipit-source-id: f330896dae9da7cbe101b1c6d7ed07667fb7ae0a

desktop/flipper-server-core/src/plugins/PluginManager.tsx

@@ -27,6 +27,7 @@ import {
   getInstalledPluginDetails,
   getInstalledPlugins,
   getPluginVersionInstallationDir,
+  getPluginDirNameFromPackageName,
   installPluginFromFile,
   removePlugins,
   getUpdatablePlugins,
@@ -129,7 +130,10 @@ export class PluginManager {
       `Downloading plugin "${title}" v${version} from "${downloadUrl}" to "${installationDir}".`,
     );
     const tmpDir = await getTempDirName();
-    const tmpFile = path.join(tmpDir, `${name}-${version}.tgz`);
+    const tmpFile = path.join(
+      tmpDir,
+      `${getPluginDirNameFromPackageName(name)}-${version}.tgz`,
+    );
     try {
       const cancelationSource = axios.CancelToken.source();
       if (await fs.pathExists(installationDir)) {