Create task "script" context

Create something like task context that can be initialised before task starts and refreshed whenever code decides to do so via some call.

Use case:

• We have multi-node multithreaded bulk task to recompute users. We want to check assignments based on targetOid against predefined list of org. units and decide on whether to remove assignment or not.
• It would be great if we could code something in the task that queries repository for list of org. units (in our case two lists) and then makes it available from some map probably in bulk action execute-script code.
• Also it would be great to have option to "clear" this context or force refresh it. Something like task cache map.

Currently we have to query DB via sql to get two lists of oid and modify task before upload - eg. task is different for each environment that we have.