[lldb] Support file and function names in LLDB_LOGF macro

LLDB's logging machinery supports prepending log messages with the name
of the file and function that generates the log. However, currently this
functionality is limited to the LLDB_LOG macro. I meant to do this as a
follow up to D65128 but never got around to it.

Differential revision: https://reviews.llvm.org/D151764