[TASK] Use URL API in Install Tool router

The Install Tool router attempts to build URLs manually by wild string
replacements and manipulation, which is rather error-prone. This patch
changes the approach to use the URL API instead.

Resolves: #101789
Releases: main, 12.4
Change-Id: I07ee73764b4fc5167f732d67faf2843fef0db199
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/80745


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Reviewed-by: Benjamin Franzke <ben@bnf.dev>