[RN] Add unlock room function to mobile

lang/main.json

         "rejoinNow": "Rejoin now",
         "maxUsersLimitReachedTitle": "Maximum members limit reached",
         "maxUsersLimitReached": "The limit for maximum number of members has been reached. The conference is full. Please contact the meeting owner or try again later!",
+        "lockRoom": "Lock room",
         "lockTitle": "Lock failed",
         "lockMessage": "Failed to lock the conference.",
         "warning": "Warning",

react/features/room-lock/actions.js

 export function _openPasswordRequiredPrompt(conference: Object) {
     return openDialog(PasswordRequiredPrompt, { conference });
 }
+
+/**
+ * Unlocks the current jitsi conference.
+ *
+ * @returns {Function}
+ */
+export function unlockRoom() {
+    return (dispatch: Dispatch<Function>, getState: Function) => {
+        const { conference } = getState()['features/base/conference'];
+
+        return dispatch(setPassword(
+            conference,
+            conference.lock,
+            ''
+        ));
+    };
+}

react/features/room-lock/components/RoomLockButton.js

 import { connect } from 'react-redux';
 
 import { translate } from '../../base/i18n';
+import { isLocalParticipantModerator } from '../../base/participants';
 import { AbstractButton } from '../../base/toolbox';
 import type { AbstractButtonProps } from '../../base/toolbox';
 
-import { beginRoomLockRequest } from '../actions';
+import { beginRoomLockRequest, unlockRoom } from '../actions';
 
 type Props = AbstractButtonProps & {
 
     /**
-     * The current conference.
+     * Whether the current local participant is a moderator, therefore is
+     * allowed to lock or unlock the conference.
      */
-    _conference: Object,
+    _localParticipantModerator: boolean,
 
     /**
      * Whether the current conference is locked or not.
      * @returns {void}
      */
     _handleClick() {
-        this.props.dispatch(beginRoomLockRequest());
+        const { dispatch, _locked } = this.props;
+
+        if (_locked) {
+            dispatch(unlockRoom());
+        } else {
+            dispatch(beginRoomLockRequest());
+        }
     }
 
     /**
      * @returns {boolean}
      */
     _isDisabled() {
-        return !this.props._conference;
+        return !this.props._localParticipantModerator;
     }
 
     /**
  * @param {Object} state - The Redux state.
  * @private
  * @returns {{
- *     _audioOnly: boolean
+ *     _localParticipantModerator: boolean,
+ *     _locked: boolean
  * }}
  */
 function _mapStateToProps(state): Object {
     const { conference, locked } = state['features/base/conference'];
 
     return {
-        _conference: conference,
+        _localParticipantModerator:
+            Boolean(conference && isLocalParticipantModerator(state)),
         _locked: Boolean(conference && locked)
     };
 }

react/features/room-lock/components/RoomLockPrompt.native.js

                 onCancel = { this._onCancel }
                 onSubmit = { this._onSubmit }
                 textInputProps = { _TEXT_INPUT_PROPS }
-                titleKey = 'toolbar.lock' />
+                titleKey = 'dialog.lockRoom' />
         );
     }