[proof-manager-cli] Add a CLI tool for stakes, proofs and delegation management

Summary:
It contains the following commands:

• decode
• sign
• validate
• delegate
• get-id
• generate-keypair

If they need to be described then the API is bad.

It takes either hex or json as input so we can store the objects in human readable format. Use proof-manager help for full details.

Depends on D18602.

Test Plan:

cargo build
cargo test

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D18610