UI Component: Backup wallet to file

[iamonuwa]

Is your feature request related to a problem? Please describe.
As a user, I want to backup my wallet to file

Describe the solution you'd like
This feature will allow the users to backup their wallet to file

1. User selects to backup a wallet data file for his wallet
2. If the file is not protected by a passphrase, e.g. with a bio auth method that user is asked to provide a pin / passprhase to protected the file data and the file data is encrypted with a key derived from the user's passphrase.
3. On desktop, the app opens the OS file explorer (Finder, Explorer, etc...) in the file's directory and ideally selects the file
4. On mobile, the app opens the save to file option as the file is in the encrypted native app local store. 5. User can save his file to a cloud file storage or to the local file system

See Wallet Restore for guide

Describe alternatives you've considered

Additional context
Cross-platform components should be put in a shared folder

See CONTRIBUTING.md for contribution guidelines

[avive]

Let's please remove all guidelines from issues and link to contributing.md