Make debug builds more usable (#4683)

* Make debug builds more usable

This pr makes debug builds more usable in terms of `cargo run -- --dev`.

1. `--dev` activates `--execution native`, iff `--execution` is not
given or no sub `--execution-*` is given.
2. It was probably a mistake to compile WASM in debug for a debug build.
So, we now build the WASM binary always as `release` (if not requested
differently by the user). So, we trade compilation time for a better
debug experience.

* Make sure we only overwrite default values

* Make it work

* Apply suggestion

substrate/client/executor/runtime-test/build.rs

@@ -21,7 +21,7 @@ fn main() {
 		"wasm_binary.rs",
 		WasmBuilderSource::CratesOrPath {
 			path: "../../../utils/wasm-builder",
-			version: "1.0.8",
+			version: "1.0.9",
 		},
 		// This instructs LLD to export __heap_base as a global variable, which is used by the
 		// external memory allocator.