XWIKI-21170: Improve the error message shown when the PDF export size limit is exceeded
XWIKI-20881: Don't enforce the size limit on single page PDF exports

* Cache failures
* Properly dispose the caches
* Only send requests to trusted domains
* Only embed actual images
* Limit responses to 1MB
* Introduce configuration options for timeout, maximum size and if the
  feature is enabled at all
* Add a UI test that checks that attachment embedding is working in
  general
* Move to httpclient5
* Expose the cookie domains configuration in AuthenticationConfiguration

* Finish removing things I had missed + add missing revapi violations (thanks Simon)

  * Remove the property from xwiki.properties.vm and the only usage of
    it in XWiki.java
  * Move all deprecated APIs that are no longer used to legacy
  * Add revapi ignores related to aspectj bug (see:
    https://github.com/eclipse-aspectj/aspectj/issues/246)

* Moved to https://github.com/xwiki-attic/xwiki-platform-chart-plugin

  * Move code and components for live email notifications with
    post-filtering to legacy modules
  * Deprecate configuration method related that check if prefiltering is
    enabled as it's now the standard
  * Remove the configuration from xwiki.properties to turn off
    prefiltering
  * Move deprecated NotificationManager to legacy
  * Move the API NotificationConfiguration#isEventPrefilteringEnabled to legacy and every implementations relying on it too

Co-authored-by: Thomas Mortagne <thomas.mortagne@xwiki.com>

XWIKI-21011: Mail resender script service API resends all mails when called from a subwiki
XWIKI-21015: Missing legacy instance APIs in distribution
* Also add missing EM categories
* Fix typo in MailResender.xml (in the "from" test)
* Make the resender scheduer job execute as XWiki.superadmin
* Male the MailResender.xml document customizable instead of demo to avoid deleting it (it's now an official feature)
* Add debug logs when resending mail
* Fix mail resender scheduler typo in description

Previous work was about introducing strategies to group events for creating
composite events. This work is about strategies for chosing how many
mails should be sent for each composite event to notify by email.
Historically the strategy was hardcoded and consisted in putting all
composite events in the same email. Here we provide different
strategies: the previous one, but also a strategy allowing to send one
email per composite event, and another one allowing to send a separate
email specifically for mentions.

That work also improves previous API to use a clear UserReference
instead of a String which is vague.

Co-authored-by: Manuel Leduc <manuel.leduc@xwiki.com>
Co-authored-by: Thomas Mortagne <thomas.mortagne@xwiki.com>

XWIKI-20937: Add support for configuring an user property to be displayed as hint by the user picker

Currently translated at 100.0% (4 of 4 strings)

Translation: XWiki Platform/Jetty listener
Translate-URL: https://l10n.xwiki.org/projects/xwiki-platform/jetty-listener/uk/

* update documentation

[Misc] Update minimal java version to 11 + add warning only when java > 17 (since Java 17 is the LTS and we support it now)

[Misc] Removing reference to XRENDERING-616 now that it's closed + Removing bad "--add-opens" (java.concurrent doesn't exist, it's java.util.concurrent), already covered by the open on "java.util"

[Misc] Removing bad "--add-opens" (java.concurrent doesn't exist, it's java.util.concurrent), already covered by the open on "java.util"

* Add the What's New extension to XS

* Update link to allowed HTML tags (and attributes, to keep them in
  sync) in the configuration.

* Fix error (thanks Thomas for checking)

XWIKI-20578: tool packager plugin ouputs lots of errors related to missing URLConfiguration component (#2062)

  * Use a Provider<URLConfiguration> in InternalSkinManager to avoid
    dependency issues with tool packager plugin
  * Add a new ComponentManagerInitializer in the tool packager plugin to
    handle unregistering the stuff we don't need for packaging
  * Add missing comment

This reverts commits
  * d56fd930
  * 1ea01e4c
  * f1393f94

  * re-apply changes previously done
  * Add missing quoting during URI parsing to avoid parse errors.
  * Provide new API to obtain a safe URI based on a string
  * Fix since and doc

Co-authored-by: Michael Hamann <michael.hamann@xwiki.com>

- Introduce an internal role (DefaultXARExtensionIndex) to know if a document is provided by an extension
- Split index-api to index-api/index-default to be able to use the api in oldcore
- Fix the escaping in invitation-ui
- Provide an automatic fix during upgrade for potential escaping issues in generated code