A new PSR-14 based event "SlugRedirectChangeItemCreatedEvent"
is introduced, allowing extension authors to create additional
redirects for a changed page slug or to remove redirect source
candidates. This is especially useful to ensure creation of
related redirects. This can be used to create redirects for
special page types or sources build by fully respecting
configured route enhancers and decorators.

Custom source implementation must be provided based on already
available `RedirectSourceInterface`. Further events in later
steps of the process with dedicated follow-up changes will
reveal the full-power, which has been kicked-off with the
streamlining of #99188 and this change.

Current behaviour of creating redirects only based on the raw
slug value are kept by implementing a specific EventListener
for it. Extensions can replace the plain slug replacment source
by registering their listeners after the core listener.

TYPO3 core may implement and ship an additional source listener
for building source uri using the page router for page type "0",
therefore repspecting configured enhancers and decorators in a
dedicated patch.

Resolves: #99746
Related: #99188
Releases: main
Change-Id: I84356d00eda48d04d5bb35d90dc1fa3141698c75
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77633


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>