Revert "remove redundant NamedSource::name (shadows new SourceCode::name)"

This reverts commit 9f18e69f6e0e9e670d56c8eec66937d62f0bc0da.

src/named_source.rs

@@ -30,6 +30,11 @@ impl NamedSource {
         }
     }
 
+    /// Gets the name of this `NamedSource`.
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
     /// Returns a reference the inner [`SourceCode`] type for this
     /// `NamedSource`.
     pub fn inner(&self) -> &(dyn SourceCode + 'static) {