Rephrase *cycle time* to *cycle point*

Fix tests for cylc 6.
When checking whether a suite is running or not, allow reasons to
contain all lines of the `pgrep` command.
Fix `date_format` in `rose.date`.

Simply return `TimePoint` object if format string is `None`.
Fix `rose_prune` test
Cylc 6 updates

Rephrase *cycle time* to *cycle point*.
Suite log/job/ and work/ restructure.
ROSE_TASK_LOG_DIR: new environment varaible, alias of CYLC_TASK_LOG_ROOT.
Rose Bush templates no longer force Z timezone.