The timestamp is localtime, so if output files are moved across time
borders, they become less valuable then they could be.
If this is important to someone, then add the ability to save a timezone
and dst attribute in the status output of xml files.
e.g.
<status status="FAIL" starttime="20200909 12:38:31.781"
endtime="20200909 12:38:31.788" timezone="10.0" dst="0"></status>

Use module variables to specify an 'override' for the timestamp into
utc.
User must change use_utc_timestamp module variable for utc to be used.
Allowing for this as current timestamp is in local time, so use in
databases may result in invalid date time search results if not set to
same timezone.

Use module variables to specify an 'override' for the timestamp into
utc and or iso8601 format.
User must call default_to_iso8601() if they wish to use it, prior to
doing an timestamp functionality.
Borrow parsing routines from https://github.com/salabs/TestArchiver.
Allowing for this as current timestamp is in local time without timezone
informatoin, so it is unclear in output files when exactly the test was
run.

To prepare for allowing iso8601utc option to be selected by the user add
a commandline options or setting for it.
Initially we will only allow iso8601utc as a value here, but theoretically
this could become an arbitrary time format string in time. That would
require a much larger rewrite of utils/robottime though.

…tions

If the user specifies iso8601utc as the timestampformat update the
robottime module by calling default_to_utc_timestamp() and
default_to_iso8601() which will globally adjust the module to output
timestamps in iso8601 utc with Z as suffix.
e.g. 2020-09-10T06:59:11.436Z
The intent is that in the future arbitrary formats could be specified.

Raising the base exception meant that higher level functions which were
passing on ValueError failed incorrectly. Changing to throw a ValueError
ensure alternate parse methods are used.

e.g. on Get Time keyword, NOW is used and results in a normalised time
of 'NOW00000 00:00:00.000', which results in an exception when parsing,
hence acceptance and unit tests were failing.

The units tests test for a time format of
"%Y%m%d %H:%M:%S:%f"
so add it into the allowed time formats.

to be parsed to allow for adjusting timestamp options which
effect logger also.
Move location of the log to ensure the application log is first.

To avoid duplicate 'timestamp' prefixes for command line arguments
modify the new argument slightly.