Use validators in CLI interface

Closes: #152 (closed)

This MR:

• Creates a dedicated SetPasswordValidator instead of defining low-level Length validator
• Adds the usage of PublicKeyAliasValidator , SetPasswordValidator, AccountNameValidator, PrivateKeyValidator, PathValidator to the existing CLI commands
• Adds length restriction to PublicKeyAliasValidator (maxwidth=50 as we need to accept also public key which has the length of 50)
• Adds liquid asset parser (including better asset type validation error message which previously was raw unreadable error from schemas)
• Adds AssetAmountValidator validation during Asset.from_legacy call