augur curate I/O: validate records have same fields

[joverlee521]

Description of proposed changes

Validate records have the same fields before and after the subcommand modifies the records.

Includes a functional test to check for the input error, but there's no good way to check for the output error. Hopefully we just never see it!

Related issue(s)

Resolves #1510

Checklist

• [x] Checks pass
• [x] If making user-facing changes, add a message in CHANGES.md summarizing the changes in this PR

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 69.60%. Comparing base (c679fde) to head (d84a0f4).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1518 +/- ## ========================================== + Coverage 69.54% 69.60% +0.05% ========================================== Files 73 73 Lines 7786 7801 +15 Branches 1904 1908 +4 ========================================== + Hits 5415 5430 +15 Misses 2086 2086 Partials 285 285 ```

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[joverlee521]

Rebased on to master to ensure no merge conflicts in changelog and updated changelog.