[FrameworkBundle] fixed requirement of the _controller palceholder for the proxy route (closes symfony#6783)

A controller name can be a service and service names can contain dots.

Author: fabpot

src/Symfony/Bundle/FrameworkBundle/Resources/config/routing/proxy.xml

@@ -4,5 +4,7 @@
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://symfony.com/schema/routing http://symfony.com/schema/routing/routing-1.0.xsd">
 
- <route id="_proxy" pattern="/_proxy/{_controller}.{_format}" />
+ <route id="_proxy" pattern="/_proxy/controller/{_controller}/format/{_format}">
+ <requirement key="_controller">.+</requirement>
+ </route>
 </routes>