Use the tmux-sessionizer from GitHub

Use the tmux-sessionizer code from GitHub instead of writing it myself
and apply a patch to change the directories it uses to provide
suggestions.

nix/pkgs/tmux-sessionizer/default.nix

@@ -0,0 +1,27 @@
+{ pkgs, ... }:
+
+pkgs.stdenv.mkDerivation rec {
+  pname = "tmux-sessonizer";
+  version = "0.1.0";
+
+  src = pkgs.fetchFromGitHub {
+    owner = "theprimeagen";
+    repo = "tmux-sessionizer";
+    rev = "master";
+    sha256 = "bZXt9TyMU1Ed/WR0/ahMQ4oyIi6yXLKnXKYPPNBt/s4=";
+  };
+
+  buildInputs = with pkgs; [
+    bash
+    fzf
+    tmux
+  ];
+
+  patches = [ ./configure-directories.patch ];
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp tmux-sessionizer $out/bin/tmux-sessionizer
+    chmod +x $out/bin/tmux-sessionizer
+  '';
+}