[web] Allow displaying multiple modals
Summary:
Modified Modal API to allow displaying multiple modals in a stack.
Used array indexes as keys for rendering array of modals, as they never changes between renders - we only push or pop modals from the stack.
Linear: https://linear.app/comm/issue/ENG-967/allow-displaying-multiple-modals-in-a-stack
Test Plan:
Tested the feature by adding temporary an action displaying confirmation modal after clicking on member in MembersModal.
Try displaying all existing modals to confirm, their behavior remain unchanged after introducing modal API changes.
Reviewers: palys-swm, benschac, atul
Reviewed By: palys-swm
Subscribers: ashoat, palys-swm, Adrian, atul, karol-bisztyga, benschac, yayabosh
Differential Revision: https://phabricator.ashoat.com/D3665