feat: add lifecycle.Executor to manage autostart and autostop (#1183)

This PR adds a package lifecycle and an Executor implementation that attempts to schedule a build of workspaces with autostart configured.

- lifecycle.Executor takes a chan time.Time in its constructor (e.g. time.Tick(time.Minute))
- Whenever a value is received from this channel, it executes one iteration of looping through the workspaces and triggering lifecycle operations.
- When the context passed to the executor is Done, it exits.
- Only workspaces that meet the following criteria will have a lifecycle operation applied to them:
  - Workspace has a valid and non-empty autostart or autostop schedule (either)
  - Workspace's last build was successful
- The following transitions will be applied depending on the current workspace state:
  - If the workspace is currently running, it will be stopped.
  - If the workspace is currently stopped, it will be started.
  - Otherwise, nothing will be done.
- Workspace builds will be created with the same parameters and template version as the last successful build (for example, template version)

cli/server.go

@@ -39,6 +39,7 @@ import (
 	"github.com/coder/coder/cli/cliui"
 	"github.com/coder/coder/cli/config"
 	"github.com/coder/coder/coderd"
+	"github.com/coder/coder/coderd/autobuild/executor"
 	"github.com/coder/coder/coderd/database"
 	"github.com/coder/coder/coderd/database/databasefake"
 	"github.com/coder/coder/coderd/devtunnel"
@@ -343,6 +344,11 @@ func server() *cobra.Command {
 				return xerrors.Errorf("notify systemd: %w", err)
 			}
 
+			lifecyclePoller := time.NewTicker(time.Minute)
+			defer lifecyclePoller.Stop()
+			lifecycleExecutor := executor.New(cmd.Context(), options.Database, logger, lifecyclePoller.C)
+			lifecycleExecutor.Run()
+
 			// Because the graceful shutdown includes cleaning up workspaces in dev mode, we're
 			// going to make it harder to accidentally skip the graceful shutdown by hitting ctrl+c
 			// two or more times.  So the stopChan is unlimited in size and we don't call