Add validateCriteria util

[ThatOneBro]

This would be helpful for validating criteria in several places, including preventing invalid criteria from being entered during AccessPolicy creation. The initial implementation can be simple and just validate the format; later on we can also check for valid search parameters and values (eg. validate that references in the criteria exist)

[mattwiller]

This is mostly resolved by #5170 — that checks for the correct format (a search string with query parameters)