Tests: Add time emulation feature for tests with BEREMIZ_TEST_CYCLES CFLAG.

Adding BEREMIZ_TEST_CYCLES=1000 in a project's CFLAGS will:
- run 1000 cycles with no pause
- emulate time flowing normaly for PLC code
- exit PLC thread

This allows:
- testing standard library blocks that deal with time without having to wait
- unit testing and code coverage with POUs that uses time

<?xml version='1.0' encoding='utf-8'?>
<BeremizRoot URI_location="LOCAL://">
  <TargetType/>
  <Libraries Enable_SVGHMI_Library="true"/>
</BeremizRoot>