Validate select (multiple choice) values.

[kmtracey]

Extend the existing validity checking (had been added just for dates) to also include validing that select values match values provided for the property in the data dictionary. As with dates, do this if and only if the feature flag for data dictionary import validation is enabled.

Summary

Feature Flag

Product Description

Safety Assurance

• Risk label is set correctly
• All migrations are backwards compatible and won't block deploy
• The set of people pinged as reviewers is appropriate for the level of risk of the change
• If QA is part of the safety story, the "Awaiting QA" label is used
• I have confidence that this PR will not introduce a regression for the reasons below

Automated test coverage

QA Plan

Safety story

Rollback instructions

• This PR can be reverted after deploy with no further considerations