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-config/src/lib.rs

@@ -390,8 +390,6 @@ async fn start_listening<
                 Ok(w) => w,
                 Err(_) => return ConfigState::Failed,
             };
-            let msg = T::get_entry(&config);
-            _ = output.send((id, msg)).await;
 
             match T::get_entry(&config) {
                 Ok(t) => {