refactor: Rename appearance to theme (#3237)

* refactor: Rename appearance to theme

* fix

* update changelog

* rename theme_dark to theme--dark

* add about migration

src/actions/actionGroup.tsx

@@ -134,7 +134,7 @@ export const actionGroup = register({
     <ToolButton
       hidden={!enableActionGroup(elements, appState)}
       type="button"
-      icon={<GroupIcon appearance={appState.appearance} />}
+      icon={<GroupIcon theme={appState.theme} />}
       onClick={() => updateData(null)}
       title={`${t("labels.group")} — ${getShortcutKey("CtrlOrCmd+G")}`}
       aria-label={t("labels.group")}
@@ -181,7 +181,7 @@ export const actionUngroup = register({
     <ToolButton
       type="button"
       hidden={getSelectedGroupIds(appState).length === 0}
-      icon={<UngroupIcon appearance={appState.appearance} />}
+      icon={<UngroupIcon theme={appState.theme} />}
       onClick={() => updateData(null)}
       title={`${t("labels.ungroup")} — ${getShortcutKey("CtrlOrCmd+Shift+G")}`}
       aria-label={t("labels.ungroup")}