Ineligibility Date Selection Bug

Issue Description

When setting a student as ineligible from their profile, the date field in the eligibility pop-up does not work correctly in Firefox. Users may be unable to select a date, and the current interface also requires use of the calendar picker instead of allowing a date to be typed manually.

Reproduce the issue in Firefox from a student's profile and open the eligibility pop-up; start by inspecting the date field and its surrounding frontend entry point. Done means users can select an ineligibility date in Firefox and type a date manually without relying on the calendar picker.

Written by the indexing model from the issue text.