Break withLegacyMatrixClient into a util module

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

src/utils/withLegacyMatrixClient.js

@@ -0,0 +1,31 @@
+/*
+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 PropTypes from "prop-types";
+import {MatrixClient} from "matrix-js-sdk";
+
+// Higher Order Component to allow use of legacy MatrixClient React Context
+// in Functional Components which do not otherwise support legacy React Contexts
+export default (Component) => class extends React.PureComponent {
+    static contextTypes = {
+        matrixClient: PropTypes.instanceOf(MatrixClient).isRequired,
+    };
+
+    render() {
+        return <Component {...this.props} matrixClient={this.context.matrixClient} />;
+    }
+};