Make it consistent for OperatorBase usage (#15908)

Make it consistent for OperatorBase usage (#15908)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15908

"OperatorBase::" is changed to "this->template ".

For example,

  # This no longer works
  OperatorBase::GetSingleArgument<>()
  # Should change to:
  this->template GetSingleArgument<>()

https://fb.workplace.com/groups/101100140348621/permalink/576804082778222/

Follow up of D13574832.

Sample Diff:
D9319742, D10045844.

Reviewed By: jspark1105

Differential Revision: D13613574

fbshipit-source-id: 2cb4094557b4af78d41e289816cad3e1194fb82c