[RN] Fix documentation comments

* Javadoc introduced @code as a replacement of <code> and <tt> which is
  better aligned with other javadoc tags such as @link. Use it in the
  Java source code. If we switch to Kotlin, then we'll definitely use
  Markdown.

* There are more uses of @code in the JavaScript source code than <tt>
  so use @code for the sake of consistency. Eventually, I'd rather we
  switch to Markdown because it's easier on my eyes.

* Xcode is plain confused by @code and @link. The Internet says that
  Xcode supports the backquote character to denote the beginning and end
  of a string of characters which should be formatted for display as
  code but it doesn't work for me. <tt> is not rendered at all. So use
  the backquote which is rendered itself. Hopefully, if we switch to
  Markdown, then it'll be common between JavaScript and Objective-C
  source code.

react/features/authentication/actionTypes.js

@@ -31,7 +31,7 @@ export const STOP_WAIT_FOR_OWNER = Symbol('STOP_WAIT_FOR_OWNER');
 /**
  * The type of (redux) action which informs that the authentication and role
  * upgrade process has finished either with success or with a specific error.
- * If <tt>error</tt> is <tt>undefined</tt>, then the process succeeded;
+ * If {@code error} is {@code undefined}, then the process succeeded;
  * otherwise, it failed. Refer to
  * {@link JitsiConference#authenticateAndUpgradeRole} in lib-jitsi-meet for the
  * error details.

react/features/authentication/actions.js

@@ -129,7 +129,7 @@ export function stopWaitForOwner() {
  *
  * @param {Object} thenableWithCancel - The process of authenticating and
  * upgrading the local participant's role.
- * @param {Object} progressOrError - If the value is a <tt>number</tt>, then the
+ * @param {Object} progressOrError - If the value is a {@code number}, then the
  * process of authenticating and upgrading the local participant's role has
  * succeeded in one of its two/multiple steps; otherwise, it has failed with the
  * specified error. Refer to {@link JitsiConference#authenticateAndUpgradeRole}

react/features/authentication/components/WaitForOwnerDialog.native.js

@@ -100,9 +100,9 @@ class WaitForOwnerDialog extends Component {
     }
 
     /**
-     * Renders a specific <tt>string</tt> which may contain HTML.
+     * Renders a specific {@code string} which may contain HTML.
      *
-     * @param {string} html - The <tt>string</tt> which may contain HTML to
+     * @param {string} html - The {@code string} which may contain HTML to
      * render.
      * @returns {ReactElement[]|string}
      */

react/features/authentication/components/styles.js

@@ -1,7 +1,7 @@
 import { BoxModel, createStyleSheet } from '../../base/styles';
 
 /**
- * The style common to <tt>LoginDialog</tt> and <tt>WaitForOwnerDialog</tt>.
+ * The style common to {@code LoginDialog} and {@code WaitForOwnerDialog}.
  */
 const dialog = {
     marginBottom: BoxModel.margin,
@@ -9,8 +9,8 @@ const dialog = {
 };
 
 /**
- * The style common to <tt>Text</tt> rendered by <tt>LoginDialog</tt> and
- * <tt>WaitForOwnerDialog</tt>.
+ * The style common to {@code Text} rendered by {@code LoginDialog} and
+ * {@code WaitForOwnerDialog}.
  */
 const text = {
 };
@@ -20,7 +20,7 @@ const text = {
  */
 export default createStyleSheet({
     /**
-     * The style of bold <tt>Text</tt> rendered by the <tt>Dialog</tt>s of the
+     * The style of bold {@code Text} rendered by the {@code Dialog}s of the
      * feature authentication.
      */
     boldDialogText: {
@@ -29,7 +29,7 @@ export default createStyleSheet({
     },
 
     /**
-     * The style of <tt>Text</tt> rendered by the <tt>Dialog</tt>s of the
+     * The style of {@code Text} rendered by the {@code Dialog}s of the
      * feature authentication.
      */
     dialogText: {
@@ -37,7 +37,7 @@ export default createStyleSheet({
     },
 
     /**
-     * The style of <tt>TextInput</tt> rendered by the <tt>Dialog</tt>s of the
+     * The style of {@code TextInput} rendered by the {@code Dialog}s of the
      * feature authentication.
      */
     dialogTextInput: {
@@ -48,7 +48,7 @@ export default createStyleSheet({
     },
 
     /**
-     * The style of <tt>LoginDialog</tt>.
+     * The style of {@code LoginDialog}.
      */
     loginDialog: {
         ...dialog,
@@ -57,7 +57,7 @@ export default createStyleSheet({
     },
 
     /**
-     * The style of <tt>WaitForOwnerDialog</tt>.
+     * The style of {@code WaitForOwnerDialog}.
      */
     waitForOwnerDialog: {
         ...dialog,