qmmp: move to pkgs/by-name

Do the necessary adaptation to be compatible with pkgs/by-name, by
taking top-level qt6 as input instead of the individual qt modules
(qtbase, ...), which were previously explicitly taken from qt6Packages.

No rebuild.

pkgs/applications/audio/qmmp/default.nix pkgs/by-name/qm/qmmp/package.nix

···
   fetchurl,
   cmake,
   pkg-config,
-  qtbase,
-  qttools,
-  qtmultimedia,
-  wrapQtAppsHook,
+  qt6,
   # transports
   curl,
   libmms,
···
   nativeBuildInputs = [
     cmake
     pkg-config
-    wrapQtAppsHook
+    qt6.wrapQtAppsHook
   ];
 
   buildInputs = [
     # basic requirements
-    qtbase
-    qttools
-    qtmultimedia
+    qt6.qtbase
+    qt6.qttools
+    qt6.qtmultimedia
     # transports
     curl
     libmms

pkgs/top-level/all-packages.nix

···
 
   qmidinet = libsForQt5.callPackage ../applications/audio/qmidinet { };
 
-  qmmp = qt6Packages.callPackage ../applications/audio/qmmp { };
-
   qnotero = libsForQt5.callPackage ../applications/office/qnotero { };
 
   qpwgraph = qt6Packages.callPackage ../applications/audio/qpwgraph { };