Move RefreshControlMock into Jest preset files (#51530)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51530

Alternative to https://github.com/facebook/react-native/pull/50784.

`__mocks__` (and other underscored dirs) are correctly excluded from our npm package via `package.json#files`. But in this instance, this is a source file for the `jest/` directory (Jest preset within `react-native`), and should be included — fix by relocating.

Changelog:
[General][Fixed] - Fix missing RefreshControlMock source in Jest preset

Reviewed By: rshest

Differential Revision: D75215731

fbshipit-source-id: 1240344c4236288f31b16513f4df16766ad1e571