denying bootstrap on multiple control plane nodes at the same time

[smira]

Feature Request

Expose as a resource - EtcdMemberPhase:

• no other members {can bootstrap}
• waiting for other etcd members to be available (connection fails) {can bootstrap}
• successfully connected to some etcd members, but can't join (waiting) {deny bootstrap}
• bootstrapping {deny bootstrap}
• running (part of the cluster) {deny bootstrap}

Example: CACPPT bootstrapping the cluster - it has no way to tell whether node A has already been bootstrapped.

Bootstrap Talos API implementation should check the phase and deny bootstrap based on that.

talosctl bootstrap CLI:

• shouldn't require --nodes (#5237)
• should check all known control plane nodes for EtcdMemberPhase and deny bootstrap as needed (based on all control plane nodes state) (implement it as part of the Talos API client library to make it re-usable)
• should have a --force flag to skip the checks and go directly to boostrap

Description