Add support for slash commands (under Feature Flag) (#6482)

* Add support for slash commands

* Update screenshots

* Rename module `slash` to `slashcommands`

* Rename `SlashCommand` to `SlashCommandService`

* Introduce MsgType in order to send text message with a different msgtype value.

* Format file and add parameter names, add default values and cleanup

* Add isSupported parameter to filter out unsupported yet commands.

* Slash commands: disable suggestions if the feature is disabled.

* Fix sending shrug command.

* Add missing test on SuggestionsProcessor

* Add tests on MessageComposerPresenter about slash command.

* Fix import ordering

* Add missing tests on CommandExecutor

* Add missing tests in MarkdownTextEditorStateTest

* Slash commands: Improve code when sending message with prefix.

* Slash commands: Add support for /unflip

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Co-authored-by: ElementBot <android@element.io>

plugins/src/main/kotlin/extension/DependencyHandleScope.kt

@@ -106,6 +106,7 @@ fun DependencyHandlerScope.allLibrariesImpl() {
     implementation(project(":libraries:session-storage:impl"))
     implementation(project(":libraries:mediapickers:impl"))
     implementation(project(":libraries:mediaupload:impl"))
+    implementation(project(":libraries:slashcommands:impl"))
     implementation(project(":libraries:usersearch:impl"))
     implementation(project(":libraries:textcomposer:impl"))
     implementation(project(":libraries:accountselect:impl"))