Intercept cases of disabled/no integration managers

We already intercepted most of the cases where no integration manager was present, though there was a bug in many components where openAll() would be called regardless of an integration manager being available.

The integration manager being disabled by the user is handled in the IntegrationManager classes rather than on click because we have quite a few calls to these functions. The StickerPicker is an exception because it does slightly different behaviour.

This also removes the old "no integration manager configured" state from the IntegrationManager component as it is now replaced by a dialog.

src/components/views/dialogs/IntegrationsImpossibleDialog.js

@@ -0,0 +1,55 @@
+/*
+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 {_t} from "../../../languageHandler";
+import sdk from "../../../index";
+
+export default class IntegrationsImpossibleDialog extends React.Component {
+    static propTypes = {
+        onFinished: PropTypes.func.isRequired,
+    };
+
+    _onAcknowledgeClick = () => {
+        this.props.onFinished();
+    };
+
+    render() {
+        const BaseDialog = sdk.getComponent('views.dialogs.BaseDialog');
+        const DialogButtons = sdk.getComponent('views.elements.DialogButtons');
+
+        return (
+            <BaseDialog className='mx_IntegrationsImpossibleDialog' hasCancel={false}
+                        onFinished={this.props.onFinished}
+                        title={_t("Integrations not allowed")}>
+                <div className='mx_IntegrationsImpossibleDialog_content'>
+                    <p>
+                        {_t(
+                            "Your Riot doesn't allow you to use an Integration Manager to do this. " +
+                            "Please contact an admin.",
+                        )}
+                    </p>
+                </div>
+                <DialogButtons
+                    primaryButton={_t("OK")}
+                    onPrimaryButtonClick={this._onAcknowledgeClick}
+                    hasCancel={false}
+                />
+            </BaseDialog>
+        );
+    }
+}