[BUGFIX] Allow external references in AssetRenderer

This patch allows external references to be rendered.
The AssetCollector allows the registration of external references,
now the AssetRenderer also renders the output correctly.

Resolves: #90694
Releases: master
Change-Id: Ib1d63c05a1d81f20cc7e4d7567b825695f4c0224
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63643


Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Susanne Moog <look@susi.dev>