Prevent context consumption of route-context from a modal that is not routable. Making routableModals never construct a path and thereby not valid.

This is breaking in the sense if someone wanted to retrieve the Route Context from a not-routable-modal. But this is not what we want pr. default.

If you still like to do so you have to consume the context with .passContextAliasMatches() enabled on your consumption.

fixes umbraco/Umbraco-CMS#17434

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (minor updates related to the tooling or maintenance of the repository, does not impact compiled assets)

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Checklist

• If my change requires a change to the documentation, I have updated the documentation in this pull request.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.