Lock lazy properties

[bdice]

Description

While debugging #528, we identified two sets of changes that are needed for correctness.

This PR adds thread locks around Job and Project methods that lazily instantiate synced collections and HDF5 data stores.

Motivation and Context

Fixes thread safety in Job and Project classes.

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 and added all related issue and pull request numbers for future reference (if applicable). See example below.

[mikemhenry]

Maybe not in this PR -- But can we add some tests so we can catch any regressions RE thread safety?

[codecov]

Codecov Report

Merging #529 (7e69d30) into master (5709232) will increase coverage by 0.09%.
The diff coverage is 89.79%.

@@            Coverage Diff             @@
##           master     #529      +/-   ##
==========================================
+ Coverage   78.17%   78.27%   +0.09%     
==========================================
  Files          65       65              
  Lines        7039     7069      +30     
  Branches     1311     1311              
==========================================
+ Hits         5503     5533      +30     
  Misses       1231     1231              
  Partials      305      305              

Impacted Files	Coverage Δ
signac/contrib/job.py	90.55% <87.50%> (+0.58%)	⬆️
signac/contrib/project.py	85.29% <100.00%> (+0.22%)	⬆️

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[vyasr]

Maybe not in this PR -- But can we add some tests so we can catch any regressions RE thread safety?

I think this is a good idea. I've done extensive work to make synced collections thread safe, and there are tests for that, but the thread safety of job objects is far less tested. I'll make an issue for it.