Implement CheckedMetadataHashExtension (#211)

generic-template/runtime/build.rs

@@ -1,10 +1,13 @@
-#[cfg(feature = "std")]
+#[cfg(all(not(feature = "metadata-hash"), feature = "std"))]
 fn main() {
-    substrate_wasm_builder::WasmBuilder::new()
-        .with_current_project()
-        .export_heap_base()
-        .import_memory()
-        .build()
+    substrate_wasm_builder::WasmBuilder::build_using_defaults();
+}
+
+#[cfg(all(feature = "metadata-hash", feature = "std"))]
+fn main() {
+    substrate_wasm_builder::WasmBuilder::init_with_defaults()
+        .enable_metadata_hash("UNIT", 12)
+        .build();
 }
 
 /// The wasm builder is deactivated when compiling