Use Substrate from crates.io or git

[xlc]

The current submodule setup requires us to use the Substrate from frontier repo and there is not way to override it. Not even with [patch.crates-io].

This makes this almost unusable to be integrated by other projects.

[tgmichel]

The reason behind the submodule setup is that Frontier still in development and may need changes on Substrate that are not there, so we usually pin Substrate versions that fit our requirements once they are merged in.

If you need to change this while Frontier and Substrate still in pre-release, you can always fork it and change the dependency paths.

[xlc]

Just use git dependency pin to particular Substrate commit / branch should do.

Having paths = ["/path/to/substrate"] in ~/.cargo/config will allow you test against local Substrate version. This is what Polkadot does.

[tgmichel]

It is definitely another way of doing it and makes sense.