[Feature](collections): add a time.Time key codec

[facundomedica]

Summary

We are currently using sdk.TimeKey which is marked as deprecated, but there is no key codec for this in the collections package. Given that it's a fairly common object we should have it.

Problem Definition

No response

Proposed Feature

Implement the thing

[chixiaowen]

@facundomedica , hello, can I try this one?

[alexanderbez]

yes please @chixiaowen

[Paulius0112]

Hi @alexanderbez. Is see this ticket is not assigned to anyone? Is it still open? If yes, can I take it?