feat: add support for dark / light mode switching (#178)

* feat: add support for dark / light mode switching and simultaneouscustom light / dark mode themes

* refactor(color-picker): optional initial color and fallback color

* refactor: used FixedPortion for layout of the settings item

This makes sure that the control always has at least the specified portion of the available space

* refactor: make all members of the ThemeBuilder public

* refactor: add and update palette colors

* fix(theme): typo and derive PartialEq for ThemeBuilder

* fix: update color picker usage

* feat: add more variables to the theme

* fix: radius on headerbar

* fix: Theme CosmicConfigEntry impl

* chore: specify rev of taffy

* fix: theme CosmicConfigEntry missing variables

* fix: apply theme type when theme mode changes

* wip: add plus icon to empty color picker button

* chore: fix rev and imports

* refactor(color-picker): allow custom size for the icon

* refactor(color_picker): make color_button public

* update iced

cosmic-theme/src/model/light.ron

@@ -55,6 +55,15 @@ Light (
         neutral_10: (
             c: "#000000",
         ),
+        bright_green: (
+            c: "#00572C",
+        ),
+        bright_red: (
+            c: "#890418",
+        ),
+        bright_orange: (
+            c: "#792C00",
+        ),
         ext_warm_grey: (
             c: "#9B8E8A",
         ),
@@ -76,23 +85,32 @@ Light (
         ext_indigo: (
             c: "#95C4FC",
         ),
+        accent_blue: (
+            c: "#00525A",
+        ),
+        accent_red: (
+            c: "#78292E",
+        ),
+        accent_green: (
+            c: "#185529",
+        ),
         accent_warm_grey: (
-            c: "#ADA29E",
+            c: "#554742",
         ),
         accent_orange: (
-            c: "#FFD7A1",
+            c: "#624000",
         ),
         accent_yellow: (
-            c: "#FFF19E",
+            c: "#534800",
         ),
         accent_purple: (
-            c: "#D58CFF",
+            c: "#68217C",
         ),
         accent_pink: (
-            c: "#FF9CDD",
+            c: "#86043A",
         ),
         accent_indigo: (
-            c: "#95C4FC",
+            c: "#2E496D",
         ),
     )
-)
+)