Update: pipe and fifo, replace f_directory_mode with f_mode, f_file_copy()

Update: pipe and fifo, replace f_directory_mode with f_mode, f_file_copy()

Stick to only using fifo terminology in file types.

Replace f_directory_mode with f_mode, a global type to be shared between f_file, f_directory, and anything else.

Update f_file_copy() to use f_mode instead of mode_t.
This allows the caller to just send the mode.
The copy function already stats the file and processes it per file type, so it can make the decision on which mode to use.
This alleviates the need for the caller to also perform a file type stat check.