[FEATURE] Support env vars in YAML file names on import

To have a variable import chain per environment (dev, stage etc) for
example, YAML files now may contain environment variables.

Resolves: #89398
Releases: master
Change-Id: I274c8e78f1a072ba490f4844d545b3015f658409
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61955


Tested-by: Mathias Brodala <mbrodala@pagemachine.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>