This change introduces a significant refactor to the agentcontainers API
and enables periodic updates of Docker containers rather than on-demand.
Consequently this change also allows us to move away from using a
locking channel and replace it with a mutex, which simplifies usage.
Additionally a previous oversight was fixed, and testing added, to clear
devcontainer running/dirty status when the container has been removed.
Updates coder/coder#16424
Updates coder/internal#621
Mathias Fredriksson
d6c14f3d8a