Feature: Add Emoji Autocomplete on Colon Type

[Khizarshah01]

As an EmbeddedChat developer

I need to see a list of suggested emojis when I type a colon : followed by text in the message box.

So That I can quickly find and insert emojis into my message without having to remember their exact names.

Acceptance Criteria

• [ ] When a user types a colon (:) followed by at least two characters (e.g., :la), a suggestion pop-up appears above the input box.

• [ ] The pop-up displays a scrollable list of emojis that match the text typed after the colon.

This feature is already available in the main Rocket.Chat web and desktop clients, providing a faster workflow for keyboard-focused users.