Warn users to migrate when old schema is detected and enable migration CLI

[vyasr]

Description

This PR adds a check in project initialization to ensure that projects with old schemas are detected when signac fails to find a project with the current schema. The resulting check provides the user a meaningful error about how to proceed with updating their schema using our migration code. This PR also exposes a CLI for migration to complement the Python interface, providing a simpler and friendlier approach to one-off migration that is recommended by the error.

Motivation and Context

Necessary to for projects how to migrate to v2.

Checklist:

• [x] I am familiar with the Contributing Guidelines.
• [x] I agree with the terms of the Contributor Agreement.
• [x] My name is on the list of contributors.
• [x] The changes introduced by this pull request are covered by existing or newly introduced tests.
• [x] The package documentation and framework documentation in signac-docs are up to date with these changes.
• [x] I have updated the changelog and added any related issue and pull request numbers for future reference.

[codecov[bot]]

Codecov Report

Merging #816 (a87e785) into master (9aa65c0) will increase coverage by 0.12%. The diff coverage is 88.63%.

@@            Coverage Diff             @@
##           master     #816      +/-   ##
==========================================
+ Coverage   85.62%   85.75%   +0.12%     
==========================================
  Files          51       51              
  Lines        4641     4683      +42     
  Branches      917      923       +6     
==========================================
+ Hits         3974     4016      +42     
+ Misses        481      480       -1     
- Partials      186      187       +1     

Impacted Files	Coverage Δ
signac/__main__.py	77.79% <68.75%> (-0.22%)	:arrow_down:
signac/common/config.py	87.67% <100.00%> (+4.33%)	:arrow_up:
signac/contrib/migration/v0_to_v1.py	86.66% <100.00%> (+3.33%)	:arrow_up:
signac/contrib/migration/v1_to_v2.py	90.00% <100.00%> (+0.81%)	:arrow_up:
signac/contrib/project.py	89.84% <100.00%> (+0.19%)	:arrow_up:
signac/contrib/migration/__init__.py	93.10% <0.00%> (+6.89%)	:arrow_up:

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[vyasr]

I haven't tested this locally but I'm happy with the code in this PR! I'll test it with v1 projects on the next branch sometime in the near future.

I'll hold off on merging to let you try a test or two in case you catch bugs that I missed in my testing.

[bdice]

@vyasr Maybe we should wait until I rebase next and then rebase this PR?

[vyasr]

@vyasr Maybe we should wait until I rebase next and then rebase this PR?

Yes that was my plan. I was also hoping to get one or two additional testers aside from myself, but I think once the rebase is done if nobody has done additional testing at that point we can just go ahead and merge this and let people test it on the main branch.

[vyasr]

@bdice @mikemhenry if one of you would like to test this locally that would be great, otherwise I think we can go ahead and just merge this.

[vyasr]

I'm going to go ahead and merge this. People can test it out on the master branch.