samsung-unified-linux-driver (cups driver): call {pre,post}Install

Add `preInstall` and `postInstall` to the `installPhase` to
permit package overrides to add commands to the install phase.

Suggested by r-rmcgibbo bot in
https://github.com/NixOS/nixpkgs/pull/133537#issuecomment-897437621

pkgs/misc/cups/drivers/samsung/1.00.36/default.nix

···
   ];
 
   installPhase = ''
+    runHook preInstall
 
     mkdir -p $out/bin
     cp -R ${arch}/{gettext,pstosecps,rastertospl,smfpnetdiscovery,usbresetter} $out/bin
···
     cd $out/share/cups
     ln -s ../ppd .
     ln -s ppd model
+
+    runHook postInstall
   '';
 
   preFixup = ''

pkgs/misc/cups/drivers/samsung/1.00.37.nix

···
   ];
 
   installPhase = ''
+    runHook preInstall
 
     mkdir -p $out/bin
     cp -R ${arch}/{gettext,pstosecps,rastertospl,smfpnetdiscovery,usbresetter} $out/bin
···
     cd $out/share/cups
     ln -s ../ppd .
     ln -s ppd model
+
+    runHook postInstall
   '';
 
   preFixup = ''

pkgs/misc/cups/drivers/samsung/4.01.17.nix

···
   dontStrip = true;
 
   installPhase = ''
+    runHook preInstall
+
     cd Linux/${installationPath}
     mkdir -p $out/lib/cups/{backend,filter}
     install -Dm755 mfp $out/lib/cups/backend/
···
     cd -
     cd ../noarch/at_opt/share/ppd
     cp -r ./* $out/share/cups/model/samsung
+
+    runHook postInstall
   '';
 
   ppdFileCommands = [