Use RTE TextView for timeline text messages, add mention pills to messages (#1990)

* 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>

features/messages/api/build.gradle.kts

@@ -15,7 +15,7 @@
  */
 
 plugins {
-    id("io.element.android-library")
+    id("io.element.android-compose-library")
 }
 
 android {