chore: add command `create-validator`, fix previous issues

[dmvict]

PR

Features

• added command create-validator
• added cli part of query command validator (forgot about node part, I'll add with delegate query command)
• updated error handling issues, used constants for common expect messages
• updated handling of timestamps
• moved constants to separate module
• removed prefixes get_

Changes in gears

• made public constants (to get validator params)
• added trait member header with default implementation and implemented it for TxContext and BlockContext
• made public CosmosDecimalProtoString and reuse it
• added method str_type to PublicKey (diff) and debug implementation. Need to discuss the method because staking module fetches public key string types from params.

To discuss

• implementation str_type