Remove import packaged environments

[b-butler]

Note; To merge after #651

Description

Removes import_packaged_environments from the configuration.

Motivation and Context

This is a move to make #649 simpler and our dependence on signac's config to be purely at the project level in Python.

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.
• The changes introduced by this pull request are covered by existing or newly introduced tests.
• The package documentation and framework documentation in signac-docs are up to date with these changes.
• I have updated the changelog and added any related issue and pull request numbers for future reference.

[codecov]

Codecov Report

Merging #653 (26c7b56) into master (04ec120) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #653      +/-   ##
==========================================
- Coverage   79.14%   79.07%   -0.07%     
==========================================
  Files          33       33              
  Lines        3241     3231      -10     
  Branches      687      685       -2     
==========================================
- Hits         2565     2555      -10     
- Misses        535      536       +1     
+ Partials      141      140       -1     

Impacted Files	Coverage Δ
flow/environment.py	68.85% <ø> (ø)
flow/util/config.py	85.00% <ø> (-15.00%)	⬇️
flow/__init__.py	100.00% <100.00%> (+15.00%)	⬆️
flow/environments/__init__.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 04ec120...26c7b56. Read the comment docs.

[vyasr]

LGTM, once the upstream PR #651 is merged we'll just need to make sure conflicts with #652 are adequately resolved (they should be orthogonal but I suspect because of squash merging we'll have some minor issues, should be easy to resolve with a merge rather than a rebase).

[cbkerr]

Looks good to me! I didn't even know that this existed