fix(electron-updater): Allow --package-file arg to escape spaces in f…

…ilenames (#2739)

Right now package file doesn't escape spaces in the filename, which causes a bug where the package file passed to the nsis installer to be incorrect. This means that when the installer runs, it will fail on folders such as 

`C:\Users\first last\appdata\roaming\package-version.7z`

This fixes it by forcing the whole file path to be a single arg.

packages/electron-updater/src/NsisUpdater.ts

@@ -106,7 +106,7 @@ export class NsisUpdater extends BaseUpdater {
     const packagePath = this.downloadedUpdateHelper.packageFile
     if (packagePath != null) {
       // only = form is supported
-      args.push(`--package-file=${packagePath}`)
+      args.push(`--package-file="${packagePath}"`)
     }
 
     const spawnOptions = {
@@ -188,4 +188,4 @@ export class NsisUpdater extends BaseUpdater {
     }
     return false
   }
-}
+}