htop: replace individual option with 'settings' (#1844)

* htop: add some missing meters
* htop: replace individual options with 'settings'
Deprecate all options and introduce `settings` for setting htop configuration
values in Nix configuration.

Use `lib.htop` to provide `fields` and `modes` for easy access to htop's integer
configuration. And `leftMeters` and `rightMeters` functions for building the
separate `*_meters` and `*_meter_modes` attributes.

* htop: add release-notes 21.05 entry
* htop: improve deprecation warnings

Move default configuration into `settings` and make deprecated options default
to `null`. Print deprecation warnings for any option that is non-null --
i.e. only show warnings for explicitly specified deprecated options.

* htop: make self code owner of module
* release notes: fix invalid programs.htop xref

tests/modules/programs/htop/default-settings.nix

@@ -0,0 +1,13 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  config = {
+    programs.htop.enable = true;
+
+    nmt.script = ''
+      assertFileExists home-files/.config/htop/htoprc
+    '';
+  };
+}

tests/modules/programs/htop/default.nix

@@ -0,0 +1,4 @@
+{
+  htop-default-settings = ./default-settings.nix;
+  htop-example-settings = ./example-settings.nix;
+}

tests/modules/programs/htop/example-settings.nix

@@ -0,0 +1,47 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  config = {
+    programs.htop.enable = true;
+    programs.htop.settings = {
+      color_scheme = 6;
+      cpu_count_from_one = 0;
+      delay = 15;
+      fields = with config.lib.htop.fields; [
+        PID
+        USER
+        PRIORITY
+        NICE
+        M_SIZE
+        M_RESIDENT
+        M_SHARE
+        STATE
+        PERCENT_CPU
+        PERCENT_MEM
+        TIME
+        COMM
+      ];
+      highlight_base_name = 1;
+      highlight_megabytes = 1;
+      highlight_threads = 1;
+    } // (with config.lib.htop;
+      leftMeters {
+        AllCPUs2 = modes.Bar;
+        Memory = modes.Bar;
+        Swap = modes.Bar;
+        Zram = modes.Text;
+      }) // (with config.lib.htop;
+        rightMeters {
+          Tasks = modes.Text;
+          LoadAverage = modes.Text;
+          Uptime = modes.Text;
+          Systemd = modes.Text;
+        });
+
+    nmt.script = ''
+      assertFileExists home-files/.config/htop/htoprc
+    '';
+  };
+}