[FIXED JENKINS-20143] Pass full list of all possible jobs to ViewJobFilter when recurse option is set

[JENKINS-18721] Imrovement of performance - now when ListView builds up it asks for all the jobs only once. This is important because RBAC plugin each time checks permissions for all these jobs which impacts performance

non-TopLevelItem.

This is the case for instance when encountering a MavenModuleSet which
is ItemGroup<MavenModule>

The view content needs to be determined by getItems as the content can
change even without view definition modification.

https://github.com/jenkinsci/jenkins/pull/757.

This changes introduces a 'recurse' option on ListView that allows to
match using regexp jobs contained inside folders.
The full name of the
job is matched so / can be used as separator.
This allows slice and dice of jobs contained in different folders.

so iterate on itemGroup.getItems and filter by job names

Further reduce the scope of the lock to only cover jobNames access, which is mandatory. if ig.doCreateItem requires synchronization, that's a job of ig.doCreateItem implementation, not that of ListView.

But the general direction of reducing the size of the lock is correct.

Added ViewGroup.getItemGroup() so that views can be used with ItemGroups in general, not just with Hudson.

Just import changes, from hudson.model.Jenkins -> jenkins.model.Jenkins,
and Javadoc comments.
Signed-off-by: NNigel Magnay <nigel.magnay@gmail.com>

Signed-off-by: NNigel Magnay <nigel.magnay@gmail.com>

refactor the save method so that it is available to all and null safe. also added a readResolve to handle when null properties are deserialized

refactor the save method so that it is available to all and null safe. also added a readResolve to handle when null properties are deserialized