feat: Add APIs for Campaigns (#2175)

app/controllers/api/v1/accounts/campaigns_controller.rb

@@ -0,0 +1,28 @@
+class Api::V1::Accounts::CampaignsController < Api::V1::Accounts::BaseController
+  before_action :campaign, except: [:index, :create]
+  before_action :check_authorization
+
+  def index
+    @campaigns = Current.account.campaigns
+  end
+
+  def create
+    @campaign = Current.account.campaigns.create!(campaign_params)
+  end
+
+  def show; end
+
+  def update
+    @campaign.update(campaign_params)
+  end
+
+  private
+
+  def campaign
+    @campaign ||= Current.account.campaigns.find_by(display_id: params[:id])
+  end
+
+  def campaign_params
+    params.require(:campaign).permit(:title, :description, :content, :enabled, :inbox_id, :sender_id, trigger_rules: {})
+  end
+end