Extract FilterFormModal

[hextraza]

FilterFormModal is pretty close to a generic Modal component that we could use to render any subcomponent, so I think we should extend it slightly so it can be used in more ways than it is at the moment. Extract it to discvr-components and rename it to PaperModal. It should take a "title" prop instead of having the set title "Filters" in the Typography component. It should also take a prop for the subcomponent instead of hard-coding a FilterForm as its child. Rename "filterProps" to "childComponentProps" as well.

What we should end up with is the ability to call PaperModal, specify a title and a subcomponent, and pass that subcomponent arbitrary props. open and handleClose can remain the same.