Split out filters into separate `eel_hole_filters` table

[e-belfer]

Overview

What is the problem we're solving? For very simple items, this can be encapsulated in the success criteria.

As noted in #345, everytime we have new total numbers of filters (e.g., someone uses 6 filters simultaneously) we now add new columns for them. We should split these filters out into a separate table with a filter_number column, and a way to join back to the other data tables.

See the eel hole marimo notebook for some code that may already achieve this.

Success Criteria

How will we know that we're done?

• New table core_eel_hole_filters
• Table has one column per type of filter variable and one column for the filter number
• Table can be joined back to the other tables easily.

Next steps

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