MINOR: cli: Report the tgid along the FD in "show sess"

MINOR: cli: Report the tgid along the FD in "show sess"

With per-thread-group FD tables, an FD number alone is ambiguous: it is
only meaningful within the thread group of the stream that uses it. So
display the FDs of the "show sess" output in the "tgid/fd" form already
used by "show fd", both in the one-line format and in the detailed one.
In the detailed output, the FD state, update and thread masks are also
read from the owner group's table rather than from the calling
thread's one, which would report an unrelated entry when the tables
are not shared.