Add table and models to support foundational flows checks

What does this MR do and why?

Add table and models to store health checks for foundational flows as discussed in #592914.

This table will be used in a follow-up MR to store checks per (flow, group, check) later.

This is an extraction from !222152 (closed).

References

Related to #592914

How to set up and validate locally

No new queries were introduced in this MR, only tables and models.

MR acceptance checklist

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