Update close button to "finish" in filter

[rachelekm]

Filter selections are applied to recommendations on change, but it's difficult to tell those changes are applied on modal exit. Additionally, most of our modals have a "finish" button vs a modal close button to confirm changes. We should update the filters modal so that there is a "finish" button similar to other modals that functionally takes the place of a "close" button for a more intuitive, cohesive design.

[rachelekm]

Also make all modal "close" buttons sticky to prevent having to scroll down longer modals