BUGFIX: Neos redirection issue in subfolder configuration

[markusguenther]

Addressing an issue where the redirection to /neos fails when Neos runs in a subfolder. This commit introduces a new route to the defaultModule. The index action of the backend controller is responsible for ensuring the correct backend module. Additionally, consideration for the preferredStartModules configuration has been incorporated here.

Fixes: neos/neos-development-collection#4797

[markusguenther]

If this is ok, we can maybe also use it here in the neos-ui manifest

// This is an extreme case when even the top node does not exist in the given dimension
                // TODO: still find a nicer way to break out of this situation
                if (!redirectContextPath) {
                    window.location = '/neos';
                    break;
                }

[neos-bot]

🎥 End-to-End Test Recordings

• Recording 1
• Recording 2

These videos demonstrate the end-to-end tests for the changes in this pull request.

[ahaeslich]

Tested in project with subfolder configuration. Works like a charm. Thx for taking care 💖

[ahaeslich]

We will have to make sure this is not lost during upmerges as of the changes in #3682.

[mhsdesign]

yes and using this in the other /neos spot also makes absolutely sense.

.

[markusguenther]

Hmm, now the end-to-end tests are not working anymore 🙈

[mhsdesign]

sorry :D