[Console] Remove $this in closure
Merge branch '2.7'

* 2.7:
  Add LegacyPdoSessionHandler class
  fix dependency on ExtensionInterface over implementation
  [Console] Remove $this in closure
  [FrameworkBundle] forward error reporting level to insulated Client
  [VarDumper] fix and test PdoCaster
  [Config] fix error handler restoration in test