[BUGFIX] Proper form definition validation if backend language changes

If a form element property is not defined through a form editor
inspector, the "predefinedDefaults" value from the form editor setup
will be used for some data integrity checks (such properties are
immutable).

Now, such checks against the "predefinedDefaults" values are *only* used
in scenarios where form elements are newely created. All the following
integrety checks on this value will be based on hmac validation.

In addition, this patchset fixes a faulty validation in the following
(edgy) scenario:

* backend language is EN
* open the form edtior and add a ContentElement form element
* switch to another browser tab and change the backend language to DE
* clear the cache
* go back to the form editor and click the save button

This is done by getting all translations (for all backend languages)
for the untranslated! "predefinedDefaults" value and compare the
(already translated) value (from the form definition) against the
possible translations from "predefinedDefaults".

There is an extended scenario which is out of scope for fixing:

* the same scenario as above + delete the previous chosen backend
  language within the maintenance tool

Resolves: #87520
Releases: master, 9.5
Change-Id: I6f486956c24121c0065b67b4f2179301e2a344c4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60638


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Tobi Kretschmann <tobi@tobishome.de>
Tested-by: Sascha Rademacher <sascha.rademacher+typo3@gmail.com>
Tested-by: Julian Geils <j_geils@web.de>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Tobi Kretschmann <tobi@tobishome.de>
Reviewed-by: Sascha Rademacher <sascha.rademacher+typo3@gmail.com>
Reviewed-by: Julian Geils <j_geils@web.de>
Reviewed-by: Susanne Moog <look@susi.dev>