[bug]: Issues with Read Only channel options

[umangutkarsh]

Description:

Currently the following are the issues of 'read-only' channel.

1. The read-only is not set dynamically to EC but is only set after page reload.
2. The read-only is also set for admins which should not be the case.
3. No appropriate message is displayed on EC when read-only option is toggled.

Steps to reproduce:

1. Go to Rocket.Chat server
2. Set to channel to read-only and see the behaviour.

Expected behavior:

The above mentioned issues should be resolved.

Actual behavior:

readonly.webm