Move all the ContextMenu semantic helper (ARIA) components out to separate modules

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/accessibility/context_menu/MenuItemCheckbox.tsx

@@ -0,0 +1,45 @@
+/*
+Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2018 New Vector Ltd
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from "react";
+
+import AccessibleButton, {ButtonEvent, IProps as IAccessibleButtonProps} from "../../components/views/elements/AccessibleButton";
+
+interface IProps extends IAccessibleButtonProps {
+    label?: string;
+    active: boolean;
+    disabled?: boolean;
+    className?: string;
+    onClick(ev: ButtonEvent);
+}
+
+// Semantic component for representing a role=menuitemcheckbox
+export const MenuItemCheckbox: React.FC<IProps> = ({children, label, active, disabled, ...props}) => {
+    return (
+        <AccessibleButton
+            {...props}
+            role="menuitemcheckbox"
+            aria-checked={active}
+            aria-disabled={disabled}
+            tabIndex={-1}
+            aria-label={label}
+        >
+            { children }
+        </AccessibleButton>
+    );
+};