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>

db/migrate/20220808193420_add_conversation_participants.rb

@@ -0,0 +1,11 @@
+class AddConversationParticipants < ActiveRecord::Migration[6.1]
+  def change
+    create_table 'conversation_participants', force: :cascade do |t|
+      t.references :account, null: false
+      t.references :user, null: false
+      t.references :conversation, null: false
+      t.datetime 'created_at', precision: 6, null: false
+      t.datetime 'updated_at', precision: 6, null: false
+    end
+  end
+end

db/migrate/20230118155353_add_unique_index_to_conversation_participants.rb

@@ -0,0 +1,5 @@
+class AddUniqueIndexToConversationParticipants < ActiveRecord::Migration[6.1]
+  def change
+    add_index :conversation_participants, [:user_id, :conversation_id], unique: true
+  end
+end