Git Feature - Add OS support for Alpine

#782 added distro checks that excludes the Alpine distro. This has effectively broken building images with git for Alpine.

```
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> [dev_containers_target_stage 4/4] RUN --mount=type=bind,from=dev_containers_feature_content_source,source=git_0,target=/tmp/build-features-src/git_0 cp -ar /tmp/build-features-src/git_0 /tmp/dev-container-features && chmod -R 0755 /tmp/dev-container-features/git_0 && cd /tmp/dev-container-features/git_0 && chmod +x ./devcontainer-features-install.sh && ./devcontainer-features-install.sh && rm -rf /tmp/dev-container-features/git_0:
0.310 ===========================================================================
[2024-01-30T21:00:27.731Z]
0.310 Feature : Git (from source)
0.310 Description : Install an up-to-date version of Git, built from source as needed. Useful for when you want the latest and greatest features. Auto-detects latest stable version and installs needed dependencies.
[2024-01-30T21:00:27.731Z] 0.310 Id : git
0.310 Version : 1.2.0
0.310 Documentation : https://github.com/devcontainers/features/tree/main/src/git
0.310 Options :
0.310 VERSION="os-provided"
0.310 PPA="true"
0.310 ===========================================================================
0.316 Linux distro alpine not supported.
[2024-01-30T21:00:27.732Z] 0.316 ERROR: Feature "Git (from source)" (git) failed to install! Look at the documentation at https://github.com/devcontainers/features/tree/main/src/git for help troubleshooting this error.
------
```

Inizia con i controlli della distro della feature Git e con l’entry point devcontainer-features-install.sh descritto nel report. Riproduci la build della feature su un’immagine Alpine, quindi verifica che Alpine sia supportato e che l’installazione di Git venga completata senza l’errore segnalato relativo a una distro non supportata.

Scritto dal modello di indicizzazione a partire dal testo della issue.