ADD some api

* api/v1/repos/{owner}/{repo}/pulls/{number}/commits
* api/v1/repos/{owner}/{repo}/pulls/{number}/files
* api/v1/repos/{owner}/{repo}/compare/{base}...{head}

app/controllers/compare_controller.rb

@@ -0,0 +1,15 @@
+class CompareController < ApplicationController
+  # skip_before_action :require_login
+  before_action :load_repository
+
+  def index
+  end
+
+  def show
+    base_ref = Addressable::URI.unescape(params[:base])
+    @ref = head_ref = Addressable::URI.unescape(params[:head])
+    @compare_result = Gitea::Repository::Commits::CompareService.call(@owner.login, @project.identifier, base_ref, head_ref)
+
+    # render json: @compare_result
+  end
+end