Improve new KeyHelper interface

[Sean-Tedrow-LB]

Problem

I'm under the impression that the KeyHelper.sol file defined here is going to be copied to this repo.

With that updated KeyHelper, creating a key looks like this: getSingleKey(0, 6, 1, bytes(""))

In this code snippet, those three numbers, 0, 6, and 1 are magic numbers, where 0 indicates that we want to set the admin key, 6 indicates that we also want to set the pause key, and 1 indicates that we want the account key that signed this execute transaction to be used for both.

When you read the code snippet getSingleKey(0, 6, 1, bytes("")) on its own, it's very difficult to read and understand

Solution

This interface would be greatly improved by providing constants for these magic numbers.

I'm hoping that this was always the plan and that I'm just being paranoid, but it seems like we're pretty close to release, so I just want to make sure that my concerns are documented.

Alternatives

No response