[web] Pull out filterOut[Parent/Other]MembersWithENSNames to remove branching

Summary:
Context: https://phab.comm.dev/D9907?id=33305#inline-61775

Basically pulling out the filter/map functionality to separate function where input is typed to avoid cut/paste and branching.

Open to any other approaches.

Depends on D9907

Test Plan: Flow/ESlint

Reviewers: ashoat, ginsu, tomek, rohan

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D9917