Function generateOrGetPreKeys
- generateOrGetPreKeys(creds, range): { 
    lastPreKeyId: number; 
    newPreKeys: { 
        [id: number]: KeyPair; 
    }; 
    preKeysRange: readonly [number, number]; 
} Returns { 
    lastPreKeyId: number; 
    newPreKeys: { 
        [id: number]: KeyPair; 
    }; 
    preKeysRange: readonly [number, number]; 
}
lastPreKeyId: number
newPreKeys: { 
    [id: number]: KeyPair; 
}
preKeysRange: readonly [number, number]