send-multiple-scte: allow sending multiple SCTE sections at once
Sometimes client wants to send multiple SCTE events at once, either from application or as pass-through
Current code
if (mux->pending_scte35_section)
gst_mpegts_section_unref (mux->pending_scte35_section);
prevents this. Proposed changes save all SCTE into a linked list, then send one by one