Add focus hook to accept theme updates for single layers

Requires https://github.com/keyboardio/Kaleidoscope-LED-Palette-Theme/pull/4

src/Kaleidoscope/Colormap.cpp

@@ -65,6 +65,13 @@ bool ColormapEffect::focusHook(const char *command) {
          map_base_, max_layers_);
 }
 
+bool ColormapEffect::focusHookLayerwise(const char *command) {
+  return ::LEDPaletteTheme.themeFocusHandlerLayerwise(command,
+                                                      PSTR("colormap.layer"),
+                                                      map_base_,
+                                                      max_layers_);
+}
+
 }
 
 kaleidoscope::ColormapEffect ColormapEffect;

src/Kaleidoscope/Colormap.h

@@ -29,6 +29,7 @@ class ColormapEffect : public LEDMode {
   void max_layers(uint8_t max_);
 
   static bool focusHook(const char *command);
+  static bool focusHookLayerwise(const char *command);
 
  protected:
   void setup(void) final;
@@ -47,3 +48,6 @@ extern kaleidoscope::ColormapEffect ColormapEffect;
 
 #define FOCUS_HOOK_COLORMAP FOCUS_HOOK(ColormapEffect.focusHook,  \
                                        "colormap.map")
+
+#define FOCUS_HOOK_COLORMAP_LAYER FOCUS_HOOK(ColormapEffect.focusHookLayerwise, \
+                                             "colormap.layer")