Add survey banner for Hermes Debugger

Summary:
As requested by the Hermes team, this adds an internal-only banner linking to a survey for the debugger (controlled by a GK).

Gatekeeper: https://our.intern.facebook.com/intern/gatekeeper/projects/flipper_plugin_hermes_debugger_survey/

Reviewed By: mweststrate

Differential Revision: D21556848

fbshipit-source-id: df34f49f504d11bba622709df86c8475be2433eb

desktop/plugins/hermesdebuggerrn/Banner.tsx

@@ -0,0 +1,80 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import React from 'react';
+import {shell} from 'electron';
+import {styled, colors, FlexRow, Text, GK} from 'flipper';
+
+const BannerContainer = styled(FlexRow)({
+  height: '30px',
+  width: '100%',
+  justifyContent: 'center',
+  alignItems: 'center',
+  backgroundColor: '#2bb673', // Hermes green.
+});
+
+const BannerText = styled(Text)({
+  color: colors.white,
+  fontSize: 14,
+  lineHeight: '20px',
+});
+
+const BannerLink = styled(CustomLink)({
+  color: colors.white,
+  textDecoration: 'underline',
+  '&:hover': {
+    cursor: 'pointer',
+    color: '#303846',
+  },
+});
+
+const StyledLink = styled.span({
+  '&:hover': {
+    cursor: 'pointer',
+  },
+});
+
+StyledLink.displayName = 'CustomLink:StyledLink';
+
+function CustomLink(props: {
+  href: string;
+  className?: string;
+  children?: React.ReactNode;
+  style?: React.CSSProperties;
+}) {
+  return (
+    <StyledLink
+      className={props.className}
+      onClick={() => shell.openExternal(props.href)}
+      style={props.style}>
+      {props.children || props.href}
+    </StyledLink>
+  );
+}
+
+export const isBannerEnabled: () => boolean = function () {
+  return GK.get('flipper_plugin_hermes_debugger_survey');
+};
+
+export default function Banner() {
+  if (!GK.get('flipper_plugin_hermes_debugger_survey')) {
+    return null;
+  }
+  return (
+    <BannerContainer>
+      <BannerText>
+        Help us improve your debugging experience with this{' '}
+        <BannerLink href="https://fburl.com/hermessurvey">
+          single page survey
+        </BannerLink>
+        !
+      </BannerText>
+    </BannerContainer>
+  );
+}