Testing and Utils Improvements

[rlizzo]

Other utils improvements along with reducing checkout time for large commits.

Motivation and Context

Why is this change required? What problem does it solve?:

simplify testing config and improvements born from new tiledb backend development.

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• [ ] Documentation update
• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Is this PR ready for review, or a work in progress?

• [x] Ready for review
• [ ] Work in progress

How Has This Been Tested?

Put an x in the boxes that apply:

• [ ] Current tests cover modifications made
• [ ] New tests have been added to the test suite
• [x] Modifications were made to existing tests to support these changes
• [ ] Tests may be needed, but they are not included when the PR was proposed
• [ ] I don't know. Help!

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have signed (or will sign when prompted) the tensorwork CLA.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[codecov[bot]]

Codecov Report

Merging #124 into master will decrease coverage by 0.14%. The diff coverage is 87.06%.

@@            Coverage Diff             @@
##           master     #124      +/-   ##
==========================================
- Coverage   92.18%   92.03%   -0.14%     
==========================================
  Files          60       60              
  Lines        9973    10005      +32     
  Branches      993      997       +4     
==========================================
+ Hits         9193     9208      +15     
- Misses        568      582      +14     
- Partials      212      215       +3

Impacted Files	Coverage Δ
tests/test_cli.py	100% <100%> (ø)	:arrow_up:
src/hangar/backends/selection.py	100% <100%> (ø)	:arrow_up:
src/hangar/arrayset.py	90.05% <100%> (+0.07%)	:arrow_up:
tests/test_arrayset.py	100% <100%> (ø)	:arrow_up:
tests/test_checkout.py	99.81% <100%> (ø)	:arrow_up:
src/hangar/utils.py	82.99% <100%> (ø)	:arrow_up:
tests/test_backend_heuristics.py	100% <100%> (ø)	:arrow_up:
tests/conftest.py	97.56% <100%> (+0.01%)	:arrow_up:
tests/test_cli_io.py	100% <100%> (ø)	:arrow_up:
src/hangar/records/commiting.py	89.92% <33.33%> (-2.2%)	:arrow_down:
... and 2 more