Fix TYPO3 project detection to work with non existent symlinks, fixes #4326

[gilbertsoft]

The Problem/Issue/Bug:

If the typo3 folder is a symlink to a non existing target the detection fails currently.

How this PR Solves The Problem:

If the first check fails, an additional check for an existing symlink is introduced.

Manual Testing Instructions:

• Set up a TYPO3 according the legacy installation
• Rename the source folder extracted from the package
• Remove AddintionalConfiguration.php

The AddintionalConfiguration.php is not longer created during ddev start or ddev restart.

Automated Testing Overview:

Related Issue Link(s):

#4326

Release/Deployment notes:

[github-actions]

Download the artifacts for this pull request:

• all-ddev-executables.zip
• ddev-linux-amd64.zip
• ddev-linux-arm64.zip
• ddev-macos-amd64.zip
• ddev-macos-arm64.zip
• ddev-windows-amd64-installer.zip

[liayn]

Works perfectly!!

[rfay]

I tested this manually and it's good and correct.

I'm not entirely sure that we should be writing code for broken symlinks.

Thanks so much!

[liayn]

I'm not entirely sure that we should be writing code for broken symlinks.

As I talked to @gilbertsoft in the TYPO3 Slack: This is actually only necessary, as we currently use the isTYPO3App function (aka "guess if it's a TYPO3", for generating the configuration.
It would be better in this case to trust what has been provided by the user in ddev config.yaml.
But I don't know the details in the ddev well enough to decide, whether this is doable at this point.