ISIS-695: removing unused imports, fixing comments
ISIS-659: extend MementoService to support enums
ISIS-706: blob vs clob handling, also w.r.t. bulk actions

ActionModel:
- blob vs clob, use same API so far as possible (differ only in IResourceStream impl)

BulkActionsLinkFactory:
- use ActionResultResponseHandlingStrategy for dealing with lastReturnedAdapter

CssMenuItems
- consistenct in config of LinkAndLabel (for the 'noVeil' CSS class workaround for actions returning blob/clob)

@Bulk.InteractionContext.InvokedAs
- new convenience methods on this enum

ObjectAction.Filters.bulk()
- added checks that the parameter count must be 0, and must not return a Blob/Clob
- the parameter check is here because removed from...

BulkAnnotationFacetFactory
- no longer requires that action has zero params
- doing so was causing bulk facet to not be installed on contributed actions
- in any case, when bulk actions with params are eventually supported, would need to remove anyway
ISIS-707: bulk interaction facet contributed actions

ObjectActionContributee
- same set up of Bulk.InteractionContext as currently done by ActionInvocationFacetViaMethod

requires changes to:
- ObjectMemberContext
  - to provide a servicesProvider (for lookup of the bookmarkService)
- ObjectReflectorDefault
  - to initialize ObjectMemberContext
- ObjectMemberAbstract
  - to expose servicesProvider to subclasses (ie ObjectActionContributee)
- unit tests

and requires changes to:
- ServicesProvider API
  - to provide a new lookupService(Class) method
- RuntimeContextFromSession, RuntimeContextNoRuntime
  - corresponding impls
ISIS-708: BookmarkService null handling