feat: make MessageComposer middleware executors public

Author: MartinCupela

src/client.ts

@@ -243,7 +243,7 @@ type MessageComposerSetupFunction = ({
   composer: MessageComposer;
 }) => void | MessageComposerTearDownFunction;
 
-type MessageComposerSetupState = {
+export type MessageComposerSetupState = {
   /**
    * Each `MessageComposer` runs this function each time its signature changes or
    * whenever you run `MessageComposer.registerSubscriptions`. Function returned

src/messageComposer/messageComposer.ts

@@ -113,6 +113,8 @@ export class MessageComposer {
   readonly editingAuditState: StateStore<EditingAuditState>;
   readonly configState: StateStore<MessageComposerConfig>;
   readonly compositionContext: CompositionContext;
+  readonly compositionMiddlewareExecutor: MessageComposerMiddlewareExecutor;
+  readonly draftCompositionMiddlewareExecutor: MessageDraftComposerMiddlewareExecutor;
 
   editedMessage?: LocalMessage;
   attachmentManager: AttachmentManager;
@@ -123,8 +125,6 @@ export class MessageComposer {
   // todo: mediaRecorder: MediaRecorderController;
 
   private unsubscribeFunctions: Set<() => void> = new Set();
-  private compositionMiddlewareExecutor: MessageComposerMiddlewareExecutor;
-  private draftCompositionMiddlewareExecutor: MessageDraftComposerMiddlewareExecutor;
 
   constructor({
     composition,