CLI: Use `GetModuleHandleExW` to locate libjulia.dll (#54617)
This should be a more reliable look-up, since this will directly report
the path of the currently-executing libjulia.dll.
Without this PR, `LoadLibraryW` depends on the system library search
order. When the top-level executable is adjacent to `libjulia.dll` (as
it is for our binary distribution usually), then that search should be
OK.
However, applications that use Julia as a library can end up searching
the system PATH before making it to the correct `lib/julia` directory,
causing us to load the wrong version of `libjulia.dll`. In many cases,
that extra load is benign due to the stricter separation of
libraries/symbols on Windows - However, in general it's likely to be the
cause of subtle bugs.
