This new navbar component is used for every navbar in chat, full page or drawer, and any screen.
This commit also uses this opportunity to correctly decouple drawer-routes from full page routes. This will avoid having this kind of properties in components: `@includeHeader={{false}}`. The header is now defined in the parent template using a navbar. Each route has now its own template wrapped in a div of the name of the route, eg: `<div class="c-routes-threads">..</div>`.
The navbar API:
```gjs
<Navbar as |navbar|>
<navbar.BackButton />
<navbar.Title @title="Foo" />
<navbar.ChannelTitle @channel={{@channel}} />
<navbar.Actions as |action|>
<action.CloseThreadButton />
</navbar.Actions>
</navbar>
```
The full list of components is listed in `plugins/chat/assets/javascripts/discourse/components/navbar/index.gjs` and `plugins/chat/assets/javascripts/discourse/components/navbar/actions.gjs`.
Visually the header is not changing much, only in drawer mode the background has been removed.
This commit also introduces a `<List />` component to facilitate rendering lists in chat plugin.
On tablets like iPad where we allow channel and thread to be on the same screen, it was not possible to resize the panels due to code being thought for mouse events. This commit should now correctly allow for this.
The "resizer" has also been made larger to simplify touching.
No test as it's hard to test on iPad and dragging events are also complex.
This pull request is a full overhaul of the chat-composer and contains various improvements to the thread panel. They have been grouped in the same PR as lots of improvements/fixes to the thread panel needed an improved composer. This is meant as a first step.
### New features included in this PR
- A resizable side panel
- A clear dropzone area for uploads
- A simplified design for image uploads, this is only a first step towards more redesign of this area in the future
### Notable fixes in this PR
- Correct placeholder in thread panel
- Allows to edit the last message of a thread with arrow up
- Correctly focus composer when replying to a message
- The reply indicator is added instantly in the channel when starting a thread
- Prevents a large variety of bug where the composer could bug and prevent sending message or would clear your input while it has content
### Technical notes
To achieve this PR, three important changes have been made:
- `<ChatComposer>` has been fully rewritten and is now a glimmer component
- The chat composer now takes a `ChatMessage` as input which can directly be used in other operations, it simplifies a lot of logic as we are always working a with a `ChatMessage`
- `TextareaInteractor` has been created to wrap the existing `TextareaTextManipulation` mixin, it will make future migrations easier and allow us to have a less polluted `<ChatComposer>`
Note ".chat-live-pane" has been renamed ".chat-channel"
Design for upload dropzone is from @chapoi
