[TASK] Deprecate alternative fetch methods for GeneralUtility::getUrl()

In times of PSR-7, TYPO3's RequestFactory API and the underlying
Guzzle HTTP library, the wrapper method GeneralUtility::getUrl() is merely
a lazy short-hand method for fetching the contents.

It is recommended to use TYPO3's RequestFactory API for fetching remote
URLs.

For now, however, the additional arguments (sending alternative headers,
only fetching HEAD requests and return headers or headers + content,
fetching a report of what happened) are deprecated, as they have
proven to be inflexible nowadays.

Resolves: #90956
Releases: master
Change-Id: Ic7631ccf61000d0853007cf9278db6e1bab09335
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64012


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>