chore: Add controllers for conversation participants (#6462)

Co-authored-by: Aswin Dev P.S <aswindevps@gmail.com>
Co-authored-by: Sojan Jose <sojan@chatwoot.com>

app/controllers/api/v1/accounts/conversations/participants_controller.rb

@@ -0,0 +1,41 @@
+class Api::V1::Accounts::Conversations::ParticipantsController < Api::V1::Accounts::Conversations::BaseController
+  def show
+    @participants = @conversation.conversation_participants
+  end
+
+  def create
+    ActiveRecord::Base.transaction do
+      @participants = participants_to_be_added_ids.map { |user_id| @conversation.conversation_participants.find_or_create_by(user_id: user_id) }
+    end
+  end
+
+  def update
+    ActiveRecord::Base.transaction do
+      participants_to_be_added_ids.each { |user_id| @conversation.conversation_participants.find_or_create_by(user_id: user_id) }
+      participants_to_be_removed_ids.each { |user_id| @conversation.conversation_participants.find_by(user_id: user_id)&.destroy }
+    end
+    @participants = @conversation.conversation_participants
+    render action: 'show'
+  end
+
+  def destroy
+    ActiveRecord::Base.transaction do
+      params[:user_ids].map { |user_id| @conversation.conversation_participants.find_by(user_id: user_id)&.destroy }
+    end
+    head :ok
+  end
+
+  private
+
+  def participants_to_be_added_ids
+    params[:user_ids] - current_participant_ids
+  end
+
+  def participants_to_be_removed_ids
+    current_participant_ids - params[:user_ids]
+  end
+
+  def current_participant_ids
+    @current_participant_ids ||= @conversation.conversation_participants.pluck(:user_id)
+  end
+end