Merge pull request #210880 from urandom2/wordpress3

wordpress: add {pre,post}Install hooks

pkgs/servers/web-apps/wordpress/generic.nix

···
   };
 
   installPhase = ''
+    runHook preInstall
+
     mkdir -p $out/share/wordpress
     cp -r . $out/share/wordpress
+
+    runHook postInstall
   '';
 
   passthru.tests = {