Feature Request - Ability to specify a custom data-dir

[pacu]

Although the rust implementation seems to support it, the CLI does not surface the ability to specify either a directory or filenames for the wallet filenames. this means that users with multiple wallets will have to manually rename the files on the default (and only possible) locations.

suggestion:
Add a --data-dir option to the interactive CLI to specify a path where to locate or store the wallet files.

zecwallet-light-cli % ./target/release/zecwallet-cli --server localhost:9067 --data-dir "~/test_wallet/"