dashdemux: apply suggestedPresentationDelay to seek and seek range

Submitted by Wojciech Przybyl

Link to original bug (#764728)

Description

When seeking or querying a range of seek on a live stream,
suggestedPresentationDelay has to be taken into account. Currently
it is only used in streams setup. As a result seeking to live position
discards suggestedPresentationDelay and seeks to earlier time than allowed.