Add type annotations for time widgets

[harahu]

📚 Context

Continuing from where I left off in #4657

• What kind of change does this PR introduce?

  • Other, please describe: Type Annotations

🧠 Description of Changes

• Add type annotations for the time_widgets module

---

Contribution License Agreement

By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

[harahu]

@vdonato @LukasMasuch This one will fail type checking if #4733 goes through, and vice versa, since it determines whether the final cast is redundant or not. Which one do you want to process first?

[LukasMasuch]

@harahu I started looking at the #4733 first :) So, maybe we get that one merged in first.

[LukasMasuch]

One small renaming suggestion, but otherwise LGTM 👍

[harahu]

This one will fail type checking if #4733 goes through, and vice versa, since it determines whether the final cast is redundant or not. Which one do you want to process first?

@LukasMasuch It seems I was wrong about this assumption. These elements are widgets, and hence, do not use dg._enqueue. I had worked so much on non-widget elements that I was confused. Seems this PR is all ready to be merged.