Pause command should postpone task starts

Current Situation

• The <modify_spooler cmd="pause"> command does not
  • prevent tasks from being started, e.g. enqueued tasks.
  • allow running tasks for jobs that make use of the API to be continued.
• This behavior applies to releases since the introduction of the new microscheduling, see JS-946

Desired Behavior

• The Pause command should
  • prevent any tasks from starting.
  • allow any running tasks to be completed normally, including tasks for jobs that make use of the API.

Implications

• Task starts that have been prevented by a Pause command are postponed to a later point in time when the JobScheduler is continued by use of a <modify_spooler cmd="continue"> command.
  • Orders and Jobs with a repeat interval in its schedule are only started for one time when the JobScheduler is continued.
  • Each task start which was enqueued manually (by JOC or by <start_job ... /> command) is started when the JobScheduler is continued.
  • Each order which was added manually (by JOC or by <add_order ... /> command) to a job chain is started when the JobScheduler is continued.
  • Each order which does not have the initial state (normally first job chain node) is continued in the job chain when the JobScheduler is continued.
• Task starts that have been prevented by a Pause command are not always postponed to a later point in time when the JobScheduler is continued by a restart.
  • Task starts because of an order's or job's schedule get lost after a JobScheduler restart.
  • Each task start which was enqueued manually (by JOC or by <start_job ... /> command) is started after a JobScheduler restart.
  • Each order which was added manually (by JOC or by <add_order ... /> command) to a job chain is started after a JobScheduler restart.
  • Each order which does not have the initial state (normally first job chain node) is continued in the job chain after a JobScheduler restart.