Check if we can decrypt backup on download

[bramkragten]

Proposed change

Checks if a backup can be encrypted and if the current encryption key is the correct one, otherwise asks for the encryption key on download.

• if a backup decryption is unsupported it shows an info about that and download encrypted
• If the user forgot the encryption key he/she can download it encrypted

Needs:

• Add WS command backup/can_decrypt_on_download core#135662
• Support decrypting backups when downloading core#135728

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io