[JENKINS-29470] - Prevent NPE in AbstractProject.checkout when agent disconnects during the build (#3094)

[JENKINS-29470] - Prevent NPE in AbstractProject.checkout when agent disconnects during the build

(cherry picked from commit b0c5a86a)

(cherry picked from commit 9054e221)

* [JENKINS-49596] - Update Winstone to 4.1.1

* [JENKINS-49596] - Pick 4.1.2 with extended session eviction defaults

(cherry picked from commit 852ecdc5)

(cherry picked from commit e5f61e29)

* [FIX JENKINS-30909] Make sure queue is persisted reliably

* Fix tests on Windows

* Ensure Saver is thread-safe

(cherry picked from commit 72a7529a)

[JENKINS-49634] Wrong escaping of quotes in the Setup Wizard

(cherry picked from commit dcb1bcd5)

[JENKINS-49498]: Fix poorly translated sign-up string (dutch)

(cherry picked from commit 59bfe03e)

[JENKINS-34712] Always show the master node when it is offline

(cherry picked from commit b67a30f8)

(cherry picked from commit 36f7fc0d)

* Fixes for validation

* Fix for an empty agent.nExecutors

(cherry picked from commit 5c8cc459)

(cherry picked from commit 376c6a0a)

(cherry picked from commit 800668ba)

Updated SSHD Module to 2.4 to bundle SSHD Core 1.7.0

* Slave.JnlpJar.getURL did not work in some modes when core had a snapshot dependency on Remoting.

* Starting to implement Channel.Listener.read/write.

* Now obtaining response timing statistics.

* For now, avoiding timestamped snapshots, as it caused problems for #3120 which I have asked for help from @stephenc diagnosing.

* Simplified logging a bit.

* onResponse

* hudson.FilePath$Mkdirs is a lot more readable than hudson.FilePath$13.

* Specific snapshot.

* onJar

* LoggingChannelListener

* remoting.version=3.17

* Making a few test assertions more lenient to adapt to https://github.com/jenkinsci/remoting/pull/247.

LegacySecurityRealm should follow the databinding pattern

In order for this to behave more uniformly with other systems like CaC,
it's preferrable not to override the newInstance method and instead use
the standard annotation.

Issue: https://github.com/jenkinsci/configuration-as-code-plugin/issues/24

[JENKINS-48463] Update jenkins core to use  XML v1.1 

[JENKINS-22088] - Upgrade Extras Executable War from 1.36 to 1.37