fix: azure-cli falls back to pip on unknown Ubuntu codenames

[Copilot]

The azure-cli feature silently no-ops (exit 0, prints "Done!") when VERSION_CODENAME isn't in the hardcoded allowlist. On Ubuntu 26.04 (resolute), containers appear healthy but have no az binary.

Changes:

• Add resolute to AZCLI_ARCHIVE_VERSION_CODENAMES for direct apt support on Ubuntu 26.04
• Add else fallback to pip when codename/architecture is unrecognized — prevents silent failure on future releases:

if [[ "${AZCLI_ARCHIVE_ARCHITECTURES}" = *"${architecture}"* ]] && [[ "${AZCLI_ARCHIVE_VERSION_CODENAMES}" = *"${VERSION_CODENAME}"* ]]; then
    install_using_apt || use_pip="true"
else
    echo "(*) Codename '${VERSION_CODENAME}' ... not in apt archive list, falling back to pip installation."
    use_pip="true"
fi

• Bump feature version to 1.3.0
• Add install_in_ubuntu_resolute test scenario against mcr.microsoft.com/devcontainers/base:ubuntu

[Kaniska244]

@copilot The fallback mechanism is required to be tested. Test for ubuntu plucky (25.04) perhaps?

[Copilot]

@copilot The fallback mechanism is required to be tested. Test for ubuntu plucky (25.04) perhaps?

Added install_fallback_pip_ubuntu_plucky test scenario that uses mcr.microsoft.com/devcontainers/base:plucky (Ubuntu 25.04). Since plucky is not in AZCLI_ARCHIVE_VERSION_CODENAMES, this exercises the else fallback-to-pip path. See commit 5e6e6f5.