[MM-55341][MM-56894] Use electron-builder to create the MSI installer, drop support for 32-bit Windows and the NSIS installer (#3028)

* Drop 32-bit windows support

* Remove unnecessary after build script

* Enable MSI build from electron-builder

* Copy MSI installers correctly

* Change script to `windows-installer`

* Revert "Remove unnecessary after build script"

This reverts commit 65b1cccb063656916a7d12c440792ad013dff826.

* Fix duplicate installers when updating to EXE version

* Inject the app-update.yml from the NSIS installer into the MSI, have the MSI uninstall the EXE if it exists

* Cleanup old MSI builder, switch actions to use new process

* Sign PR builds

* Update to use absolute paths

* Use env variable paths

electron-builder.json

@@ -156,7 +156,8 @@
   "win": {
     "target": [
       "nsis",
-      "zip"
+      "zip",
+      "msi"
     ],
     "extraFiles": [
       {
@@ -164,13 +165,20 @@
           "LICENSE.txt",
           "NOTICE.txt"
         ]
+      },
+      {
+        "from": "resources/windows/gpo",
+        "to": "gpo"
       }
     ],
+    "signDlls": true,
     "publisherName": "CN=\"Mattermost, Inc.\", O=\"Mattermost, Inc.\", L=Palo Alto, S=California, C=US"
   },
   "nsis": {
     "artifactName": "${version}/${name}-setup-${version}-win.${ext}",
-    "packElevateHelper": false
+    "packElevateHelper": false,
+    "uninstallDisplayName": "${productName}",
+    "include": "scripts/installer.nsh"
   },
   "rpm": {
     "fpm": ["--rpm-rpmbuild-define", "_build_id_links none"]