Inaccurate description of sender-public-key flag in Commander

[bobanm]

The description for sender-public-key flag currently is quite inaccurate.

For transaction:sign:

Sign the transaction with provided sender public key, when passphrase is not provided

• conceptually: you don't sign anything using a public key
• functionally: the public key here is used to calculate the multisig account address, while the signing is done using private key which is derived from the provided passphrase
• procedurally: if passphrase is not provided in flags, a user will be prompted to enter it

For transaction:create:

Creates the transaction with provided sender publickey, when passphrase is not provided

Also, for transaction:create the description is in transaction/create.ts while the description for transaction:sign is in utils/flags.ts.

Since flag description should be the same, it should go in utils/flags.ts file, which is command independent.

A more accurate description of the flag would be:

Set a custom senderPublicKey property for the transaction, to be used when account address does not correspond to signer's private key