Plain text editor implementation based on markdown input (#2840)

* Add plain text editor based on markdown input
- Fix autofocus of message composer.
- Remove `Message` data class, fetch the details in `MessagesPresenter` instead.
- Remove `enable rich text` option from advanced settings, set it as a build configuration instead.
* Fix MentionSpanProvider
* Bump RTE library to released `v2.37.3`

---------

Co-authored-by: ElementBot <benoitm+elementbot@element.io>

libraries/preferences/api/src/main/kotlin/io/element/android/features/preferences/api/store/AppPreferencesStore.kt

@@ -19,9 +19,6 @@ package io.element.android.features.preferences.api.store
 import kotlinx.coroutines.flow.Flow
 
 interface AppPreferencesStore {
-    suspend fun setRichTextEditorEnabled(enabled: Boolean)
-    fun isRichTextEditorEnabledFlow(): Flow<Boolean>
-
     suspend fun setDeveloperModeEnabled(enabled: Boolean)
     fun isDeveloperModeEnabledFlow(): Flow<Boolean>