update SBDebugger::SetInputFile() etc to work on native Files

Summary:
This patch adds FileSP versions of SetInputFile(),
SetOutputFile, and SetErrorFile().   SWIG will convert native
python file objects into FileSP.

Reviewers: JDevlieghere, jasonmolenda, labath

Reviewed By: labath

Subscribers: clayborg, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D68734

llvm-svn: 374422