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

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

* Fix [JENKINS-49206] by ensuring Timer threads get standard classloader

* Refactor to better fit in with existing ThreadFactor utils

* Fix javadocs

* [JENKINS-48407] Re-enable test

The previous test assumed permissions would always be the same,
when they actually depend on umask settings.

This change creates a file *not* using the temporary API, gets its
permissions then compares it to the ones obtained using
AtomicFileWriter.

Note: we now only check the given permissions, not the "non-given".

* Use assertThat(..., equalTo()) instead of a manual loop

* Remove unused imports

* Use TemporaryFolder instead of manual temporary dir creation

* Introduced ACL.lambda convenience method.

* Javadoc

Separate original and downstream dependency errors

[JENKINS-47793] - Jenkins master and agent configuration pages do not verify negative executor numbers (#3141)

* Fixed Regexps for number & positive-number

* Progress saving

* Fix for validation

* bug fixing

* bug fixing

* Address comments

* Address comments

* Address comments from @jglick

* Whitespace cleanup

* Address comment for @jglick

[JENKINS-48725] - Update Lib Task Reactor to 1.5

file handle cleanup in the event of failure

Fixed small nits regarding typo's and code cleanup
Added comment explaining why Xpp3 is still included as a dep

Disable test temporarily to get the release out

Note: this test is wrong, the production code is correct.
So that is why disabling this test until we fix it is OK.

[JENKINS-49060] Include the filename of the unreadable file in the exception message

[JENKINS-24452] Don't export arbitrary unexportable exceptions

[JENKINS-49147] Tolerate unusual CodeSource.location format from old versions of Tomcat

[JENKINS-48766] - Expose information about Remoting versions via API

Remove support for unbounded number of polling threads

[JENKINS-49126] OldDataMonitor: Prevent escaping b-old version

* [JENKINS-49112] Revert use of Files.newBufferedReader() in Util.loadFile()

This partially reverts 67076834.

* Restore the use of StringBuilder and reading into buf

[JENKINS-49129] Manage Jenkins dropdown menu no longer works

in, just in case some plugin might be depending on them

Fix Spanish (es) link translation

[JENKINS-46041] If guessBrowser fails, return null and move on

new default driver

KXml2Driver being tolerant of control characters which should be illegal
in an XML v1.0 content.  This test should be revisted if we switch to
another XML driver

technically illegal xml (ie. it doesn't complain if an Xml v1.0 file
contains special characters).  Added a unit test that proves this, as well
as fixing silentlyMigrateConfigsTest so that it starts with technically
valid Xml 1.0 content

are silently migrated to xml v1.1 as they are persisted

  - verify can still read xml 1.0
  - verify can read xml 1.1
  - verify can read xml 1.1 with 'special' characters
  - verify that jenkins can start with a config.xml having
    <?xml version='1.1'> and special characters

Changed all explicit references of the hierarchical driver to use a static
convinience method XStream2.getDefaultDriver() to ensure all XML operations
are using the same driver.

[JENKINS-48463] update hard coded references of XPP3Driver to KXml2Driver in order to support XMLv1.1

  - switched to KxmlDriver (needed for xml 1.1 support)
  - updated to create xml v1.1 headers
  - updated test to use KXml2Driver explicitly
  - updated unit tests to support xml v1.1