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`

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

tests/konsist/src/test/kotlin/io/element/android/tests/konsist/KonsistPreviewTest.kt

@@ -78,6 +78,7 @@ class KonsistPreviewTest {
                 "IconTitleSubtitleMoleculeWithResIconPreview",
                 "IconsCompoundPreview",
                 "IconsOtherPreview",
+                "MarkdownTextComposerEditPreview",
                 "MentionSpanPreview",
                 "MessageComposerViewVoicePreview",
                 "MessagesReactionButtonAddPreview",