DEBUG: quic: export the few task handlers that often appear in task dumps

DEBUG: quic: export the few task handlers that often appear in task dumps

The following task/tasklet handlers often appear in "show profiling tasks"
but were not resolved since static:

 qc_io_cb, quic_conn_app_io_cb, process_timer,
 quic_accept_run, qc_idle_timer_task

This commit simply exports them so they can be resolved now. "process_timer"
which was a bit too generic and renamed to qc_process_timer.