fix: Use `.mock` extension for MMKV mocks#647

Mister-CK wants to merge 2 commits intomrousavy:mainmrousavy/react-native-mmkv:mainfrom

Mister-CK:fix/use-mock-based-on-running-configMister-CK/react-native-mmkv:fix/use-mock-based-on-running-configCopy head branch name to clipboard