Queueing, prepping to fetch

A lot more to go, but this is the core.

Need to think about how to test the queue handlers.

internal/types/base.go

@@ -0,0 +1,9 @@
+package types
+
+import (
+	"context"
+
+	"git.jadud.com/jadudm/grosbeak/internal/liteq"
+)
+
+type QueueWorker func(ctx context.Context, job *liteq.Job) error