Proposed changes

When an agent wants to join a new livechat, appears a button Take it as a preview mode, and when he click on Take it the button needs to hide and appear an input text.

Issue(s)

The agent is assigned to the chat, but there's no reactivity, which means the agent needs to "refresh" the room in order to see the message composer.

How to test or reproduce

1 - Activate Omnicahnnel -> https://docs.rocket.chat/guides/omnichannel-guides/omnichannel-admins-guide
2 - Set Manual Selection as Omnichannel routing system -> https://docs.rocket.chat/guides/omnichannel-guides/omnichannel-admins-guide/queue-types-routing-algorithm#manual-selection
3 - Start a new chat through Livechat
4 - Go to Omnichannel Queue (Mobile)
5 - Open an incoming chat
6 - Click on Take it! button

Screenshots

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

Further comments