The draft-proposal command introduced a Prompt (https://github.com/cosmos/cosmos-sdk/blob/701aaa8/x/gov/client/cli/prompt.go) helper, that prompts the user of each field.

We should move Prompt to client/v2 and use the scalar annotation instead of simple field matching for validating the fields.
Additionally, the Prompt should work recursively on the whole message.

ref: #15982 (comment)