Prevent workspaces from being kept alive when they should not

Functional duplicate of https://github.com/coder/vscode-coder/issues/309 for the Jetbrains extension.

When users stop their workspaces in the dashboard, an idle jetbrains gateway session may reconnect them, and start the workspace when the user is not present. This can incur unnecessary costs for administrators while devs are not active.

We should copy the behavior [Asher describes here](https://github.com/coder/vscode-coder/issues/309#issuecomment-2195472060) if possible.

> Is there a workspace build going on? If so, wait for that build.
> Is the workspace on? If not, prompt to start the workspace and depending on the response go back to 1 or quit.
> Otherwise wait for the agent to be ready then connect, or exit if the agent enters some failed/off state.