[FEATURE] Ext:form - extend the extension location functionality

With this patch is it possible to:

* save existing forms within extension locations
  ("allowedExtensionPaths") if "allowSaveToExtensionPaths"
  is set to true (like before)
* save new created forms within extension locations
  ("allowedExtensionPaths") if "allowSaveToExtensionPaths"
  is set to true
* delete forms within extension locations ("allowedExtensionPaths")
  if "allowDeleteFromExtensionPaths" is set to true

Resolves: #79250
Releases: master
Change-Id: I2d06448f7ee9a0ab0a249ddfee750eda8aeee54e
Reviewed-on: https://review.typo3.org/51254


Tested-by: TYPO3com <no-reply@typo3.com>
Tested-by: Tobi Kretschmann <tobi@tobishome.de>
Reviewed-by: Tobi Kretschmann <tobi@tobishome.de>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>