[JENKINS-20739] Filter descriptors before adding them to hetero-list.

This allows implementations of DescriptorVisibilityFilter to hide items
with descriptors from users to prevent them from being added via the UI.

This is already implemented in /lib/hudson/newFromList/form.jelly, but
nowhere else.
Added logging when filtering descriptors.
Abstract username case sensitivity into an extension point
[JENKINS-22247] Provide an extension point to define user id case sensitivity contract

* Fix up bad merge
Use a dedicated descriptor
Updating the pull request in light of comments

- Removed the Legacy strategy completely
- Moved the strategy to an aspect of the security realm
- Separated the strategy for Users from Groups because... well it might be necessary for some
- Moved IdStrategy from inner class of User into top level class
Updated w.r.t. pull request review comments
Fix test
Fix warnings in ListView
[FIXED JENKINS-22967] Introduce directly modifiable views
[JENKINS-22967] Polish new api
[JENKINS-22967] Make DirectlyModifiableView an interface rather than class
[JENKINS-22967] Fix item name semantics for DirectlyModifiableView web methods
[JENKINS-14979] Add actual URL redirected to to log output
memory-monitor 1.8
Merge pull request #1241 from daniel-beck/JENKINS-14979

[JENKINS-14979] Add actual URL redirected to to log output
Merge REMERGE_HEAD into HEAD
Removing apparently senseless exception.
=== Starting buildShellScriptOnSlave(org.jenkinsci.plugins.workflow.job.WorkflowTest)
.. hudson.slaves.CommandLauncher launch
INFO: slave agent launched for slave0
Exception in thread "Executor #0 for slave0 : executing org.jenkinsci.plugins.workflow.support.steps.ExecutorStep$PlaceholderTask$PlaceholderExecutable@c455a14" java.lang.IllegalStateException: Trying to remove unknown computer
	at hudson.model.AbstractCIBase.removeComputer(AbstractCIBase.java:149)
	at hudson.model.Computer.removeExecutor(Computer.java:837)
	at hudson.model.Executor.run(Executor.java:263)
Use proper array lenght

See PR #1233 and discussion therein.
(cherry picked from commit b8c3f61c907d58a024e7122a7549fff8de75a482)
[maven-release-plugin] prepare release jenkins-1.564