fix: Simplify provisionerd job acquire (#158)

This uses a simple channel to detect whether a
job is running or not, and moves all cancels
to be in goroutines.

coderd/coderd.go

@@ -23,6 +23,7 @@ type Options struct {
 func New(options *Options) http.Handler {
 	api := &api{
 		Database: options.Database,
+		Logger:   options.Logger,
 		Pubsub:   options.Pubsub,
 	}
 
@@ -110,5 +111,6 @@ func New(options *Options) http.Handler {
 // be added to this struct for code clarity.
 type api struct {
 	Database database.Store
+	Logger   slog.Logger
 	Pubsub   database.Pubsub
 }