[BUGFIX] Allow same configuration key in multiple extensions

[BUGFIX] Allow same configuration key in multiple extensions

Fix two issues in the extension configuration tool if more than one
extension is using the same configuration key:

* Remove duplicate HTML IDs in extension configuration tool
* Correctly add hidden fields with value=0 for checkboxes within every
  sub-<form>, not only on first occurence (first extension) of any given
  configuration key

Resolves: #88426
Releases: master, 9.5
Change-Id: Ifbdb3b495443aa5521a4b5265ae3c29c2bc222b8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60831
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Guido Schmechel <guido.schmechel@brandung.de>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Benni Mack <benni@typo3.org>