azuredatastudio: fix file dialogs

File open dialogs in Azure Data Studio cause the application to crash.
As documented in #225989, this can be worked around by setting
XDG_DATA_DIRS, but the correct fix is to use GApps hooks. Add those to
the program packaging, and move the custom fixup phase to a pre-fixup
hook, so the main hooks also get run.

Fixes #225989

pkgs/by-name/az/azuredatastudio/package.nix

···
   openssl,
   pango,
   systemd,
+  wrapGAppsHook3,
   xorg,
   zlib,
 }:
···
   nativeBuildInputs = [
     makeWrapper
     copyDesktopItems
+    wrapGAppsHook3
   ];
 
   buildInputs = [
···
     sqltoolsserviceRpath
   ];
 
-  fixupPhase = ''
+  preFixup = ''
     fix_sqltoolsservice()
     {
       mv ${sqltoolsservicePath}/$1 ${sqltoolsservicePath}/$1_old