Adds support for tracking additional modifier columns for measurements, which can be used in downstream pipelines like UniHPF.

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.08% :tada:

Comparison is base (62d7c97) 85.17% compared to head (b5a236a) 85.26%. Report is 1 commits behind head on dev.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #58 +/- ## ========================================== + Coverage 85.17% 85.26% +0.08% ========================================== Files 34 34 Lines 6470 6481 +11 ========================================== + Hits 5511 5526 +15 + Misses 959 955 -4 ``` | [Files Changed](https://app.codecov.io/gh/mmcdermott/EventStreamGPT/pull/58?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Matthew+McDermott) | Coverage Δ | | |---|---|---| | [EventStream/data/config.py](https://app.codecov.io/gh/mmcdermott/EventStreamGPT/pull/58?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Matthew+McDermott#diff-RXZlbnRTdHJlYW0vZGF0YS9jb25maWcucHk=) | `87.79% <100.00%> (+0.37%)` | :arrow_up: | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/mmcdermott/EventStreamGPT/pull/58/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Matthew+McDermott)

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.