Fix the secondary runtime metadata

polkadot.js is broken due to the metadata RPC call panics.

```
FATAL: Unable to initialize the API: -32603: Unknown error occurred: Client error: Execution failed: Runtime panicked: All path segments should be valid Rust identifiers: InvalidIdentifier { segment: 1 }
```

It turns out `r#` is unsupported by scale-info.

cumulus/parachain-template/runtime/src/lib.rs

@@ -5,12 +5,12 @@
 // Skip in regular `no-std` environment, such that we don't cause conflicts of globally exported
 // functions
 #[cfg(any(feature = "wasm-builder", feature = "std"))]
-mod r#impl;
+mod runtime;
 
 // Skip in regular `no-std` environment, such that we don't cause conflicts of globally exported
 // functions
 #[cfg(any(feature = "wasm-builder", feature = "std"))]
-pub use r#impl::*;
+pub use runtime::*;
 
 // Make the WASM binary available, except in wasm builder environment.
 #[cfg(not(feature = "wasm-builder"))]

cumulus/test/runtime/src/lib.rs

@@ -5,12 +5,12 @@
 // Skip in regular `no-std` environment, such that we don't cause conflicts of globally exported
 // functions
 #[cfg(any(feature = "wasm-builder", feature = "std"))]
-mod r#impl;
+mod runtime;
 
 // Skip in regular `no-std` environment, such that we don't cause conflicts of globally exported
 // functions
 #[cfg(any(feature = "wasm-builder", feature = "std"))]
-pub use r#impl::*;
+pub use runtime::*;
 
 // Make the WASM binary available, except in wasm builder environment.
 #[cfg(not(feature = "wasm-builder"))]