Factor substrate node runner into separate crate (#913)

* factor out node starting thing to separate crate to use in test-runtime and integration-tests

* remove subxt dep on test-runtime build, and clippy tidyup

* remove now-unneeded dep

* Update testing/substrate-runner/Cargo.toml

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

* Update testing/integration-tests/Cargo.toml

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* remove unneeded port things for backward compat

---------

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>
Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

testing/substrate-runner/src/error.rs

@@ -0,0 +1,23 @@
+// Copyright 2019-2023 Parity Technologies (UK) Ltd.
+// This file is dual-licensed as Apache-2.0 or GPL-3.0.
+// see LICENSE for license details.
+
+#[derive(Debug)]
+pub enum Error {
+    Io(std::io::Error),
+    CouldNotExtractPort,
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::Io(err) => write!(f, "IO error: {err}"),
+            Error::CouldNotExtractPort => write!(
+                f,
+                "could not extract port from running substrate node's stdout"
+            ),
+        }
+    }
+}
+
+impl std::error::Error for Error {}