added hash type codes

[rlizzo]

Motivation and Context

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

Add type codes for hashes used to calculate data hash digests.

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)
• [x] New feature (non-breaking change which adds functionality)
• [x] 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:

• [x] Current tests cover modifications made
• [ ] New tests have been added to the test suite
• [ ] 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 #165 into master will increase coverage by 0.02%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #165      +/-   ##
==========================================
+ Coverage   95.14%   95.16%   +0.02%     
==========================================
  Files          65       66       +1     
  Lines       11831    11878      +47     
  Branches     1024     1029       +5     
==========================================
+ Hits        11256    11303      +47     
- Misses        384      385       +1     
+ Partials      191      190       -1

Impacted Files	Coverage Δ
tests/test_commit_ref_verification.py	100% <ø> (ø)	:arrow_up:
src/hangar/records/parsing.py	98.52% <100%> (+0.02%)	:arrow_up:
tests/property_based/test_pbb_valid_hash_tcodes.py	100% <100%> (ø)
tests/property_based/test_pbt_arrayset.py	100% <100%> (ø)	:arrow_up:
src/hangar/cli/cli.py	89.52% <100%> (ø)	:arrow_up:
tests/test_remote_serialize.py	100% <100%> (ø)	:arrow_up:
src/hangar/remote/server.py	77.47% <100%> (+0.18%)	:arrow_up:
src/hangar/records/commiting.py	89.92% <100%> (ø)	:arrow_up:
tests/test_dataloaders.py	98.88% <100%> (ø)	:arrow_up:
src/hangar/records/hashmachine.py	100% <100%> (ø)	:arrow_up:
... and 6 more