Startup message could be improved in Pyinstaller

[lbeckman314]

Currently the "Initializing ..." message on startup (#50) is written directly into the Pyinstaller bootloader (due to the Splash Screen feature not being currently being supported on macOS):

bootloader/src/pyi_main.c

// If only one temp dir is found then we can assume that we're in the parent 
// and should output the "Initializing ..." message
if (count == 1) {
    printf("Initializing ...\n");
}

The issue with the current logic is that if more than one DRS Downloader process is started, only the first process will output the startup message.

A more robust approach might be to update Pyinstaller to create a temporary "parent" directory for each new intitial process in which subsequent calls to the bootloader can extract files into (each multiprocessing Python process calls the same bootloader on startup).

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Could leverage the runtime_tmpdir arguments in the EXE class of Pyinstaller:

PyInstaller/building/api.py

self.runtime_tmpdir = kwargs.get('runtime_tmpdir', None)

Which is then passed to the function responsible for making the temp directory to unpack the archive:

bootloader/src/pyi_archive.c

/* Check for custom run-time temporary directory options */
runtime_tmpdir = pyi_arch_get_option(status, "pyi-runtime-tmpdir");
if (runtime_tmpdir != NULL) {
    VS("LOADER: Found runtime-tmpdir %s\n", runtime_tmpdir);
}