Add Marker support to be able to schedule tasks

[burakkoken]

This feature makes it easier to schedule task by using markers and code generation.
The following markers should be added, they will be enough for now.

• +chrono:scheduled. This should have the following arguments.
  FixedDelay, FixedRate, Cron
• +chrono:enable-scheduling
  (main method should be marked with this annotation, it will enable support for scheduling)

The simple rule that we need to follow to marker a method with +chrono:scheduled is:
The method should have the method signature as shown below. (If not, the method will be ignored or an error message will be shown.)

func(ctx context.Context)

Please investigate how to support this feature.