Move test crates into a "testing" folder and add a ui (trybuild) test and ui-test helpers (#567)

* move test crates into a testing folder and add a ui test and helpers

* undo wee mixup with another PR

* cargo fmt

* clippy

* tidy ui-tests a little

* test different DispatchError types

* refactor dispatch error stuff

* name ui tests

* duff => useless

* align versions and cargo fmt

testing/integration-tests/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+name = "integration-tests"
+version = "0.21.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2021"
+
+license = "GPL-3.0"
+readme = "../README.md"
+repository = "https://github.com/paritytech/subxt"
+documentation = "https://docs.rs/subxt"
+homepage = "https://www.parity.io/"
+description = "Subxt integration tests that rely on the Substrate binary"
+
+[features]
+default = ["subxt/integration-tests"]
+
+[dev-dependencies]
+assert_matches = "1.5.0"
+codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive", "full", "bit-vec"] }
+frame-metadata = "15.0.0"
+futures = "0.3.13"
+hex = "0.4.3"
+scale-info = { version = "2.0.0", features = ["bit-vec"] }
+sp-core = { version = "6.0.0", default-features = false  }
+sp-keyring = "6.0.0"
+sp-runtime = "6.0.0"
+subxt = { version = "0.21.0", path = "../../subxt" }
+test-runtime = { path = "../test-runtime" }
+tokio = { version = "1.8", features = ["macros", "time"] }
+tracing = "0.1.34"
+tracing-subscriber = "0.3.11"
+wabt = "0.10.0"
+which = "4.0.2"