timeshift: patch timeshift-launcher with escapeShellArg instead of a patch file

pkgs/applications/backup/timeshift/timeshift-launcher.patch

@@ -1,26 +0,0 @@
-diff --git a/src/timeshift-launcher b/src/timeshift-launcher
-index 29b8fc4..5f6cb17 100755
---- a/src/timeshift-launcher
-+++ b/src/timeshift-launcher
-@@ -1,6 +1,6 @@
- #!/bin/bash
- 
--app_command='timeshift-gtk'
-+app_command=''"$(realpath "$(dirname "$0")")"'/timeshift-gtk'
- 
- if [ "$(id -u)" -eq 0 ]; then
- 	# user is admin
-@@ -14,11 +14,11 @@ else
- 		# script is running in non-interactive mode
- 		if [ "$XDG_SESSION_TYPE" = "wayland" ] ; then
- 			xhost +SI:localuser:root
--			pkexec ${app_command}
-+			pkexec env DISPLAY="$DISPLAY" XAUTHORITY="$XAUTHORITY" "${app_command}"
- 			xhost -SI:localuser:root
- 			xhost
- 		elif command -v pkexec >/dev/null 2>&1; then
--			pkexec ${app_command}
-+			pkexec env DISPLAY="$DISPLAY" XAUTHORITY="$XAUTHORITY" "${app_command}"
- 		elif command -v sudo >/dev/null 2>&1; then
- 			x-terminal-emulator -e "sudo ${app_command}"
- 		elif command -v su >/dev/null 2>&1; then

pkgs/applications/backup/timeshift/unwrapped.nix

@@ -26,10 +26,6 @@ stdenv.mkDerivation rec {
     hash = "sha256-2qNLgUZLMcfoemdLvvjdkR7Ln5loSKGqbd402y5Id8k=";
   };
 
-  patches = [
-    ./timeshift-launcher.patch
-  ];
-
   postPatch = ''
     for FILE in src/Core/Main.vala src/Utility/Device.vala; do
       substituteInPlace "$FILE" \
@@ -38,6 +34,10 @@ stdenv.mkDerivation rec {
 
     substituteInPlace ./src/Utility/IconManager.vala \
       --replace-fail "/usr/share" "$out/share"
+
+    substituteInPlace ./src/timeshift-launcher \
+      --replace-fail "app_command='timeshift-gtk'" ${lib.escapeShellArg ''app_command="$(realpath "$(dirname "$0")")/timeshift-gtk"''} \
+      --replace-fail ${lib.escapeShellArg ''pkexec ''${app_command}''} ${lib.escapeShellArg ''pkexec env DISPLAY="$DISPLAY" XAUTHORITY="$XAUTHORITY" "''${app_command}"''}
   '';
 
   nativeBuildInputs = [