This diff updates disposeTempFile to use expo-file-system instead of react-native-fs, and correspondingly update all callsites to pass in a URI instead of a path.

Initial context here.

Note that there are still some scattered calls to react-native-fs's unlink in other parts of the codebase.

Depends on D14636

1. Tested media save flow on Android
2. Read the docs and code for react-native-fs and expo-file-system to determine which can take a file path vs URI
3. Read my changes carefully to make sure there are no problems