feat: support force updating to latest version

[FrederikBolding]

Allows updating to the latest version by specifying version: 'latest'. This has always been supported but would not force an update until now.

If the user already has a Snap installed and the origin specifies latest we will now assume consent to use the allowlist and/or NPM to resolve the latest version. After doing that we will continue the update flow with the resolved version instead of *.

Fixes https://github.com/MetaMask/MetaMask-planning/issues/1002

WIP