Function from_user_hosts_expression_to_xname_vec 

pub async fn from_user_hosts_expression_to_xname_vec(
    infra: &InfraContext<'_>,
    shasta_token: &str,
    hosts_expression: &str,
    is_include_siblings: bool,
) -> Result<Vec<String>, Error>

Convenience wrapper that fetches node metadata from the backend and resolves a hosts expression to a sorted, deduplicated list of xnames.

Combines the two-step pattern of [ComponentTrait::get_node_metadata_available] (called on the backend held in InfraContext) followed by from_hosts_expression_to_xname_vec that recurs in many command files.