feat: Added a Threads menu to easily access ongoing threads in a channel.

[Spiral-Memory]

Brief Title

Added a new section "Threads menu" where users can navigate through ongoing threads in the channel, search for different messages, and navigate directly to those threads.

Acceptance Criteria Fulfillment

• [x] Identified the correct modal in which we can display ongoing threads.
• [x] Designed it consistently with the original Rocket.Chat design and reused existing components in the embedded chat.
• [x] Since the message was already retrieved, used the global message state and filtered through the messages that are threads and not just messages or other notifications.
• [x] Each thread in the menu is clickable, allowing users to navigate directly to that thread.
• [x] Threads are searchable, enabling users to easily search through thread messages.
• [x] Created a UI for "No Thread Messages" to inform users when there are no threads that match the search.
• [x] Also checked the showAvatar state that can be given as props and will be disabled when set to false.

Fixes #441

Video/Screenshots

The following video demonstrates how it works:

https://github.com/RocketChat/EmbeddedChat/assets/78961432/9ef0a24f-46e0-4089-9cb5-457e5ff89f05

The following screenshot shows that the avatar will be displayed only when enabled:

[Akshun-01]

Great work! 🙌

• I want to point out that it should be confined to the chat area only.? (Like starting from the header till where the message box ends.) Because this may it might cause issue when integrated into other apps, right?

[Spiral-Memory]

Great work! 🙌

• I want to point out that it should be confined to the chat area only.? (Like starting from the header till where the message box ends.) Because this may it might cause issue when integrated into other apps, right?

Actually, I had a similar thought while working on this, but currently, modals are designed that way. In another issue, my plan is that once the sidebar opens, the chat body and chat header will shrink to the other side just like it happens in the original Rocket chat application, preventing the sidebar from overlapping, as well as it should confine to the place where chat body is. Also the same is true for other modals as well like channel information, members etc. So that issue has to be addressed globally for all the sidebar modals. I'm already working on this and will soon discuss it with the maintainers and will implement the same. Thank you for your feedback and appreciation, @Akshun-01