Add option to create wallet from seed or audit key

[aguycalled]

This PR adds the option to create a wallet from a master key or an audit key. The master key of a wallet can be obtained using the RPC command getblsctseed; while the audit key can be obtained with getblsctauditkey.

Two options to create a wallet:

• Using the navio-wallet tool together with the option seed. Example:
  navio-wallet -blsct -chain=blsctregtest -wallet=wallet_name -seed="71187dc33c03914c630e87b205777d51f7bd2749bc1164795e0134544d43d9ee" create
• Using the rpc command createwallet. Example:
  navio-cli --blsctregtest -named createwallet wallet_name=wallet_name blsct=true seed="71187dc33c03914c630e87b205777d51f7bd2749bc1164795e0134544d43d9ee"

[mxaddict]

Changes look good

[aguycalled]

Working for me:

# sudo -u navio navio-wallet -blsct -testnet -wallet=w -seed= 6af514afff0602109742d6d818d607fa5242d7b6af514afff0602109742d6d818d60 create
Topping up keypool...
Wallet info
===========
Name: w
Format: sqlite
BLSCT: yes
Descriptors: no
Encrypted: no
HD (hd seed available): yes
Keypool Size: 64
Transactions: 0
Address Book: 0
# sudo -u navio navio-cli loadwallet w
{
  "name": "w"
}
# sudo -u navio navio-cli -rpcwallet=w getblsctseed
6af514afff0602109742d6d818d607fa5242d7b6af514afff0602109742d6d818d60
# sudo -u navio navio-cli -named createwallet blsct=true wallet_name=w2 seed=6af514afff0602109742d6d818d607fa5242d7b6af514afff0602109742d6d818d60
{
  "name": "w2"
}
# sudo -u navio navio-cli -rpcwallet=w2 getblsctseed
6af514afff0602109742d6d818d607fa5242d7b6af514afff0602109742d6d818d60

[mxaddict]

I don't understand what this was testing, would like to know more if you can explain