src.ctf.fs: move struct ctf_fs_trace and struct ctf_fs_port_data up

src.ctf.fs: move struct ctf_fs_trace and struct ctf_fs_port_data up

Move them so they are before ctf_fs_component.  This enables the
following patches to use a unique_ptr to hold them in ctf_fs_component.

Change-Id: If97956d0c74795f8ee18ecebe035c8b186d85a2b
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8239
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12278