Add ProfileSearchRequest

[betsyecastro]

Implements ValidSearchString validation rule on ProfileSearchRequest to fix Sentry issue 6S - Array to string conversion and to improve the input validation on the search field.

Github issue #48

[shukla-m]

@betsyecastro I reviewed the code and tested it locally and the string validation works as expected. Additional validations can be added as needed, but this update works for validating that the search input value is a string.

cc: @wunc

[betsyecastro]

@wunc I used the htmlspecialchars() function with the FILTER_FLAG_NO_ENCODE_QUOTES flag to convert any unwanted special characters that passed the regex validation into their HTML-escaped equivalents. However, I’ve been discussing with @shukla whether this is the most appropriate approach for preventing SQL injection, since we need to allow apostrophes for searchable input — which means they’ll still be included in the $search wildcard used in the query.

What are your thoughts on this? If you’re available Friday or Monday, perhaps we could review it together with Shukla. Thank you.