[TASK] Add Error Codes to Page Failure Reasons

A new class with constants is added to make the TYPO3 internal errors
why a page cannot be displayed in the frontend more speakable.

Resolves: #17794
Releases: master
Change-Id: I8b9999e95f109666a524ee9157f89f498b21ca6d
Reviewed-on: https://review.typo3.org/57201


Reviewed-by: Nicole Cordes <typo3@cordes.co>
Tested-by: Nicole Cordes <typo3@cordes.co>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Daniel Sattler <sattler@b13.de>
Tested-by: Daniel Sattler <sattler@b13.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>