clock-rs: add module

clock-rs is a modern, digital clock that effortlessly runs in your terminal

tests/modules/programs/clock-rs/example-settings.nix

@@ -0,0 +1,42 @@
+{ pkgs, ... }:
+{
+  config = {
+    programs.clock-rs = {
+      enable = true;
+      settings = {
+        general = {
+          color = "magenta";
+          interval = 250;
+          blink = true;
+          bold = true;
+        };
+
+        position = {
+          horizontal = "start";
+          vertical = "end";
+        };
+
+        date = {
+          fmt = "%A, %B %d, %Y";
+          use_12h = true;
+          utc = true;
+          hide_seconds = true;
+        };
+      };
+    };
+
+    nmt.script =
+      let
+        configDir =
+          if pkgs.stdenv.isDarwin then
+            "home-files/Library/Application Support/clock-rs"
+          else
+            "home-files/.config/clock-rs";
+      in
+      ''
+        assertFileExists "${configDir}/conf.toml"
+        assertFileContent "${configDir}/conf.toml" \
+            ${./example-settings-expected.toml}
+      '';
+  };
+}