feat(package): ad-hoc sign macOS bundles (#1656)

* feat(package): ad-hoc sign macOS bundles

* fix(package.sh): syntax error

* docs(readme): add instructions for self-signed builds

* docs(readme): grammar

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

---------

Co-authored-by: Guldoman <giulio.lettieri@gmail.com>

README.md

@@ -95,7 +95,17 @@ Lite XL will load and store all your configurations and plugins in the folder.
 We provide DMG files for macOS. Simply drag the program into your Applications folder.
 
 > **Important**
-> Since Lite XL is not signed, you **must** run this command before starting Lite XL:
+> Newer versions of Lite XL are signed with a self-signed certificate,
+> so you'll have to follow these steps when running Lite XL for the first time.
+>
+> 1. Find Lite XL in Finder (do not open it in Launchpad).
+> 2. Control-click Lite XL, then choose `Open` from the shortcut menu.
+> 3. Click `Open` in the popup menu.
+>
+> The correct steps may vary between macOS versions, so you should refer to
+> the [macOS User Guide](https://support.apple.com/en-my/guide/mac-help/mh40616/mac).
+>
+> On an older version of Lite XL, you will need to run these commands instead:
 > 
 > ```sh
 > # clears attributes from the directory

scripts/package.sh

@@ -264,6 +264,11 @@ main() {
     $stripcmd "${exe_file}"
   fi
 
+  if [[ $bundle == true ]]; then
+    # https://eclecticlight.co/2019/01/17/code-signing-for-the-concerned-3-signing-an-app/
+    codesign --force --deep -s - "${dest_dir}"
+  fi
+
   echo "Creating a compressed archive ${package_name}"
   if [[ $binary == true ]]; then
     rm -f "${package_name}".tar.gz