avfilter/drawtext: present 'hms' formatted 'pts' in 24h format

avfilter/drawtext: present 'hms' formatted 'pts' in 24h format

HMS is formatted as HH:MM:SS.mmm, but, HH part is not limited to
24 hours. For example, the the drawn text may look like this:
243029:20:30.342. To present the timestamp in more readable and
user friendly format, this patch provides an additional option
to limit the hour part in the range 0-23.

Note: Actually the above required format can be obtained with
format options 'localtime' and 'gmtime', but,  milliseconds part
is not supported in those formats.