Fix starship deps

[schlich]

This pull request updates the Starship devcontainer feature by bumping its version, improving its installation script, and adding a basic test. The changes focus on improving reliability and maintainability.

Version and dependency updates:

• Bumped the version field in devcontainer-feature.json from 0.1.5 to 0.1.6 and added a dependency on common-utils for better feature interoperability.

Installation improvements:

• Changed the shebang in install.sh from /bin/sh to /bin/env bash to ensure bash is found anywhere in PATH.

Testing enhancements:

• Added a new test script test.sh to verify that the starship binary is available in the path after installation.