Add support for actions in engine

Methods in MuranoPL now can be marked with Usage attribute
to specify whether particular method available for remote
call or not. By default usage is Runtime (not available for
remote call).

Workflow:
  migrateVm:
    Usage: Action
    Arguments:
      - killExisting:
          Contract: $.bool()
          Default: True

Change-Id: If3da3c6bf67aa79d522d82abbf3b5378f72e87ae
Partially-Implements: blueprint application-actions
Merge "Add support for actions in engine"