FR: array-not-contains support in firestore

[atsjo]

Operating System

Environment (if applicable)

Firebase SDK Version

Firebase SDK Product(s)

Firestore

Project Tooling

Detailed Problem Description

I am using hacky and non-efficient workarounds today to find docs where I am not member, the elegant solution would be array-not-contains... (and possibly array-not-contains-any)

Steps and code to reproduce issue