Replace status and value with add_info

[btjanaka]

Description

To make the, more flexible, add() methods now return add_info instead of separate status_batch and value_batch. This will make it easy to return more info in the future.

Correspondingly, emitters now take in add_info instead of separate status_batch and value_batch arguments, and calls to add() have been fixed in the schedulers.

TODO

• Update in ArchiveBase
• Update in SlidingBoundariesArchive
• Update calls in scheduler
• Update emitters to take in add_info
• Fix tests

Questions

Status

• I have read the guidelines in
  CONTRIBUTING.md
• I have formatted my code using yapf
• I have tested my code by running pytest
• I have linted my code with pylint
• I have added a one-line description of my change to the changelog in
  HISTORY.md
• This PR is ready to go