Feature: Action System (#298)

* Add Action System

- Add keyboard test
- Add context menu label
- Add PanelComponent

* Show context menu items based on actions

* Add render action feature

- Replace bringForward etc buttons with action manager render functions

* Move all property changes and canvas into actions

* Remove unnecessary functions and add forgotten force update when elements array change

* Extract export operations into actions

* Add elements and app state as arguments to `keyTest` function

* Add key priorities

- Sort actions by key priority when handling key presses

* Extract copy/paste styles

* Add Context Menu Item order

- Sort context menu items based on menu item order parameter

* Remove unnecessary functions from App component

src/actions/types.ts

@@ -0,0 +1,57 @@
+import React from "react";
+import { ExcalidrawElement } from "../element/types";
+import { AppState } from "../types";
+
+export type ActionResult = {
+  elements?: ExcalidrawElement[];
+  appState?: AppState;
+};
+
+type ActionFn = (
+  elements: readonly ExcalidrawElement[],
+  appState: AppState,
+  formData: any
+) => ActionResult;
+
+export type UpdaterFn = (res: ActionResult) => void;
+
+export interface Action {
+  name: string;
+  PanelComponent?: React.FC<{
+    elements: readonly ExcalidrawElement[];
+    appState: AppState;
+    updateData: (formData: any) => void;
+  }>;
+  perform: ActionFn;
+  keyPriority?: number;
+  keyTest?: (
+    event: KeyboardEvent,
+    elements?: readonly ExcalidrawElement[],
+    appState?: AppState
+  ) => boolean;
+  contextItemLabel?: string;
+  contextMenuOrder?: number;
+}
+
+export interface ActionsManagerInterface {
+  actions: {
+    [keyProp: string]: Action;
+  };
+  registerAction: (action: Action) => void;
+  handleKeyDown: (
+    event: KeyboardEvent,
+    elements: readonly ExcalidrawElement[],
+    appState: AppState
+  ) => ActionResult | {};
+  getContextMenuItems: (
+    elements: readonly ExcalidrawElement[],
+    appState: AppState,
+    updater: UpdaterFn
+  ) => { label: string; action: () => void }[];
+  renderAction: (
+    name: string,
+    elements: ExcalidrawElement[],
+    appState: AppState,
+    updater: UpdaterFn
+  ) => React.ReactElement | null;
+}