Stop passing file and line around
SourceLocation cannot be confused with other parameters as it's a distinct type.
It also has better information (function and column), and can be implicitly generated by the special default parameter compiler intrinsics (a la std::source_location).

Use BOOST_SOURCE_LOCATION to deal with platform compatibility.

It will find the __builtin_LINE() etc functions needed for the SourceLocation default parameter behavior.
https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html#index-_005f_005fbuiltin_005fLINE
These features are supported by all of our compilers even if std::source_location isn't yet.

We can get rid of MONGO_SOURCE_LOCATION_NO_FUNC.