Move scripts to Nix files

Move the scripts I commonly use into Nix files managed by Home Manager.

Some, like `mounter` and `unmounter` are desktop-only, but this can be
addressed in a future commit to create per-host scripts or
desktop/non-desktop scripts.

This commit also removes a number of unused scripts that are either
included in packages like `git-extras` or aren't used.

modules/home-manager/cli/scripts/create-script.nix

@@ -0,0 +1,21 @@
+{ pkgs }:
+
+pkgs.writeShellApplication {
+  name = "create-script";
+
+  text = ''
+    cat > "$1" << EOF
+    #!/usr/bin/env bash
+
+    set -o errexit
+    set -o nounset
+    set -o pipefail
+
+
+    EOF
+
+    chmod +x "$1"
+
+    $EDITOR "$1";
+  '';
+}