feature: expose the distribution type for use by features in choosing installation paths

[Common-utils has a bit of baseline distribution identification](https://github.com/devcontainers/features/blob/fbdc4556d519512736a8e2abfb3e03fcb2c9e0c7/src/common-utils/main.sh#L293) - enough to know what kind of package manger is in play, so that you can have a feature that doesn't just assume Debian and `apt-get` availability. Rather than making all feature developers replicate this bit of code, it would be hugely beneficial to drop it into a function and return a value so that `install.sh` scripts could use that information to know how to proceed with various distributions, or even to report that other distributions just "aren't supported" for that feature.

(related to https://github.com/orgs/devcontainers/discussions/33)

Beginne mit der Distributionsidentifikationslogik in src/common-utils/main.sh ungefähr bei Zeile 293 und überprüfe, wie die install.sh-Skripte der Features derzeit Paketmanager auswählen. Definiere den wiederverwendbaren Rückgabewert und seine Verwendung für unterstützte und nicht unterstützte Distributionen und überprüfe anschließend die betroffenen Installationspfade anhand repräsentativer Features.

Vom Indexierungsmodell aus dem Issue-Text verfasst.