HD492 iCap Encoder: Enable Lexi Blocking via SCTE

Release Notes:

This update installs options for the type of SCTE-104 message sent to the hardware encoders that will trigger Lexi to be blocked (shutoff/pause) and unblocked (restart/resume).

When upstream VANC sent to the encoder includes a START NORMAL, trigger message with a Duration value, Lexi will be blocked (in line with when the ad break starts), with the duration value determining when Lexi becomes unblocked (in line with when the ad break ends).