Add changelog for 0.77.0-rc.7 (#48738)

Summary:
Changelog for 0.77.0-rc.7

## Changelog:
[Internal] Changelog

Pull Request resolved: https://github.com/facebook/react-native/pull/48738

Test Plan: N/A

Reviewed By: cortinico

Differential Revision: D68276563

Pulled By: robhogan

fbshipit-source-id: ae57d179d98cd5200a449adbc1b38909633b10d1