fix: use file size as first check for file integrity test, then hash

[a-ghorbani]

Description

• Modified model integrity checking to prioritize file size comparison over hash verification, has for some reason RNFS.hash not always return correct hash
• Added 0.1% size difference tolerance. Sufficient for detecting most corruption/incomplete download issues.
• Made hash checking a fallback option only when size comparison isn't possible

Fixes #172

Platform Affected

• iOS
• Android

Checklist

• Necessary comments have been made.
• I have tested this change on:
  • iOS Simulator/Device
  • Android Emulator/Device
• Unit tests and integration tests pass locally.