ir: stream: prefer to use stream's name for (CTF writer) stream's path

ir: stream: prefer to use stream's name for (CTF writer) stream's path

When creating a stream file for a given CTF writer stream object, use
this format:

    PREFIX-SCID-SID

PREFIX:
    1. Base name of stream's name, if it exists.
    2. Base name of stream class's name, if it exists.
    3. `stream`

SCID:
    Stream class's ID.

SID:
    Stream's ID.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>