Close flex-tab when opening a room on mobile UI

[danieljhochman]

Rocket.Chat Version: 0.56
This issue is more acute when running a small width window

To reproduce:
0. Make the window width small so that you can only see one screen at a time

1. From a channel, click on "members list" menu item.
2. Click on a user to start direct messaging with.
3. Start conversation
4. Then, click the hamburger menu and go back to the channel.
5. It shows the user page. It should show the chat room.

A similar issue when using a small window:

1. Perform a search
2. Click "go to message"
3. Nothing seems to happen
4. The search window needs to be closed instead so the user sees the message right away.