Support Safe Notes on iOS devices

[keshav-space]

Minimium feature needed to support Safe Notes on iOS:

• [x] #183
• [x] #189
• [x] #191
• [x] #193
• [x] #198
• [x] #200
• [x] #203
• [ ] #205
• [ ] Add Splash screen for iOS
• [ ] Redirect Rate App to Apple store on ios devices
• [ ] Optimize image with ImgBot
• [ ] Figure out an appropriate license for the App Store; GPL may be problematic
• [ ] Translation updates
  • [ ] Update backup description and translation for: Instead of daily backup, Safe Notes now intelligently performs continuous backup.
  • [ ] Add translation for: "Use device's light or dark mode setting for the app." Ref #199
  • [ ] Add translation for: "Theme" Ref #199
• [ ] Update the F-Droid recipe to use proper JDK and Flutter version.
• [ ] Publish beta test version to https://testflight.apple.com/
• [ ] Publish to iOS App store.