libs/utils/trace: add support for systrace trace format
libs/utils/trace: add support for systrace trace format

TRAPpy provides now support for parsing events from a trace embedded into
systrace, which are usually encapsulated into an HTML file.

This patch allows to specify which format a trace is and, by
default, it assumes that an HTML file contains a systrace format.

Signed-off-by: Patrick Bellasi <431c86f368affbc3148c4669fbd465131f7e82cb@arm.com>

credp/lisa,ARM-software/lisa,mdigiorgio/lisa,ARM-software/lisa,bjackman/lisa,credp/lisa,joelagnel/lisa,arnoldlu/lisa,ARM-software/lisa,bjackman/lisa,credp/lisa,ARM-software/lisa,credp/lisa,JaviMerino/lisa,mdigiorgio/lisa,joelagnel/lisa,arnoldlu/lisa