Make Requests Processes and create process hierarchy. Associate OpenRepository with context. (#17125)

This PR registers requests with the process manager and manages hierarchy within the processes.

Git repos are then associated with a context, (usually the request's context) - with sub commands using this context as their base context.

Signed-off-by: Andrew Thornton <art27@cantab.net>

options/locale/locale_en-US.ini

@@ -2696,6 +2696,7 @@ monitor.execute_time = Execution Time
 monitor.process.cancel = Cancel process
 monitor.process.cancel_desc =  Cancelling a process may cause data loss
 monitor.process.cancel_notices =  Cancel: <strong>%s</strong>?
+monitor.process.children = Children
 monitor.queues = Queues
 monitor.queue = Queue: %s
 monitor.queue.name = Name