* Add `formattedBody` to `TimelineItemTextBasedContent`.
This is pre-computed when timeline events are being mapped from the Rust SDK.
* Update `HtmlConverterProvider` styles.
* Improve `MentionSpan` to add missing `@` or `#` if needed
* Replace `HtmlDocument` with the `TextView` based component
* Improve extra padding calculation for timestamp by rounding the float offset result instead of truncating it.
* Remove composer line height workaround
* Use `ElementRichTextEditorStyle` instead of `RichTextEditorDefaults` for the theming
* Use slightly different styles for composer and messages (top/bottom line height discrepancies, mostly).
* Add `formattedBody` to notice and emote events.
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Co-authored-by: ElementBot <benoitm+elementbot@element.io>
