The schema defined in T433853: Create a table to store calculated properties for SuggestedInvestigations has gotten tentative approval (or at least hasn't been rejected outright) as of writing and is probably stable enough to develop on while waiting for creation. To display the value in T433840: Implement case filtering on "edits on shared pages" for SuggestedInvestigations it has to exist first. This value is the one calculated by SuggestedInvestigationsSharedPagesLookup::getSharedPagesForCases.

Additional tickets may be split from this depending on scale of the solution.

Acceptance criteria:

• On case creation, calculate and cache value of "edits on shared pages count"
• On edit from an account tied to a case, invalidate the case's cached value and recalculate/rewrite
• Instrument this, as we need to know if it's too expensive/if we need to downgrade live-ness