Scroll to specific message/position

[DmitriyNikolenko]

Motivation There are a couple of cases:

1. A user leaves the page for some settings page, returns back and wants to stay on the same scroll position (preserve scroll)
2. Some message in the chat is shared with a user and he wants to open it. The channel should be loaded and scrolled to the target message.

Proposed solution Provide the ability to scroll to a specific message OR scroll position.

Acceptance Criteria A user is able to open a list of channel messages in the same position when he stopped watching. A user is able to be scrolled to a specific message when he opens a channel.