[Feature]: spin out cosmossdk.io/crypto into its own module

[Zygimantass]

Summary

I'd like to import the crypto package to interact with keys / keyrings without importing the whole SDK (due to dependency issues).

It should be pretty simple to spin out as per our convo with @tac0turtle, the only problems I see are:

• the crypto package utilizes protos, which means that it imports cosmos-sdk/types/tx/amino.
• it also uses SDK errors, so it imports types/errors

Problem Definition

No response

Proposed Feature

Spin out the package into a submodule called cosmossdk.io/crypto

[raynaudoe]

Hi, this was exactly one of the main objectives of #18824.
The idea was to use this repo as a crypto module to encapsulate every crypto related code. In there there's also a first implementation of the above mentioned ADR.

[Zygimantass]

@raynaudoe i see there's symmetric key types implemented in cosmos/crypto, are there any plans for secp256k1?