Implement Shamir seed backup

[olemis]

Feature description

SLIP 39 support

Describe the solution you'd like
Implement multiple backup types in existing protocol messages.

Additional context
See Trezor's BackupType .

Refs fibercrypto/skywallet-protob#73 .

Possible implementation

• Add backup type firmware variable
• Implement backup type in GetFeatures message
• Implement backup type in Reset message