Enable aggregate status check

[kidrahahjo]

Description

This enables storing aggregate information during submission and fetches the before status printing.
This is necessary to fetch information about the missing aggregates

Motivation and Context

This is to be merged into glotzerlab/signac-flow:enable-aggregate-submission after #1
After this gets merged, glotzerlab/signac-flow:enable-aggregate-submission will be ready to get merged into glotzerlab/signac-flow:master. After that, we'll now have to introduce the aggregator classes (glotzerlab#306) into glotzerlab/signac-flow:master.

Types of Changes

• Documentation update
• Bug fix
• New feature
• Breaking change¹

¹The change breaks (or has the potential to break) existing functionality.

Checklist:

• I am familiar with the Contributing Guidelines.
• I agree with the terms of the Contributor Agreement.
• My name is on the list of contributors.
• My code follows the code style guideline of this project.
• The changes introduced by this pull request are covered by existing or newly introduced tests.

If necessary:

• I have updated the API documentation as part of the package doc-strings.
• I have created a separate pull request to update the framework documentation on signac-docs and linked it here.
• I have updated the changelog.

[kidrahahjo]

This is moved to glotzerlab#335