Remove messageInfos fileds from iOS notification if its size exceeds defined limit

Summary: This differential removes messageInfos fields from iOS notification if it is too large. Size is compared to thresholds from apple/google docs

Test Plan: Build iOS app without changes, open web app and send message large enough that notification is not generated. The introduce changes in the mobile app and send the same message. Ensure notification appears

Reviewers: tomek, jacek, ashoat

Reviewed By: tomek, ashoat

Subscribers: ashoat, adrian, atul, abosh

Differential Revision: https://phab.comm.dev/D4601