Data columns overwrite functions regardless of time unit

[lars-reimann]

What problem do you want to solve?

Closes #699

Data columns now always overwrite policy functions regardless of their time unit. If, for example, the value eink_st_y_sn is needed, and a data column eink_st_m_sn and policy function eink_st_y_sn are provided, the converted data column is used.

Todo

• [X] Pick an appropriate title.
• [X] Put Closes #XXXX in the first PR comment to auto-close the relevant issue once the PR is accepted. This is not applicable if there is no corresponding issue.
• [x] Document PR in CHANGES.md.

[codecov[bot]]

Codecov Report

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

Project coverage is 89.22%. Comparing base (0dda2de) to head (c5a5f4a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #700 +/- ## ========================================== + Coverage 89.17% 89.22% +0.05% ========================================== Files 51 51 Lines 3592 3592 ========================================== + Hits 3203 3205 +2 + Misses 389 387 -2 ```

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