Add nichart mode

[tsalo]

Closes none.

Changes proposed in this pull request

• Add a "nichart" mode that matches how the NiChart project is processing its data.
• Make the default values for --smoothing and --min-coverage "auto", since "nichart" mode has defaults that differ from the current defaults.

[codecov[bot]]

Codecov Report

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

Project coverage is 79.04%. Comparing base (7694faa) to head (cfa1385). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1320 +/- ## ========================================== + Coverage 78.96% 79.04% +0.08% ========================================== Files 59 59 Lines 7383 7412 +29 Branches 957 961 +4 ========================================== + Hits 5830 5859 +29 Misses 1261 1261 Partials 292 292 ```

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