fix(appsync): sanitized datasource name isn't exported (#23802)

Closes #23743
When providing a name with unsupported characters to an AppSync datasource, it is sanitized internally. #22378 introduced a bug where the sanitized name was no longer exposed on DataSource class instances.

----

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![image](https://user-images.githubusercontent.com/5336472/214185923-6e90b49a-e834-4932-a23a-12094546181d.png)

![image](https://user-images.githubusercontent.com/5336472/214186095-a4ee51f7-37e1-451c-ba08-d27277cba0b9.png)

The above code generates the shown diff. This is due to #23743 where the name is sanitised, but not when setting `this.name`.

packages/@aws-cdk/aws-appsync/lib/data-source.ts

@@ -125,7 +125,7 @@ export abstract class BaseDataSource extends Construct {
       serviceRoleArn: this.serviceRole?.roleArn,
       ...extended,
     });
-    this.name = name;
+    this.name = supportedName;
     this.api = props.api;
   }
 

packages/@aws-cdk/aws-appsync/test/appsync-none.test.ts

@@ -54,6 +54,20 @@ describe('None Data Source configuration', () => {
     });
   });
 
+  test('appsync data source exports sanitised name', () => {
+    // WHEN
+    const ds = api.addNoneDataSource('ds', {
+      name: 'Produce-Custom',
+    });
+
+    // THEN
+    Template.fromStack(stack).hasResourceProperties('AWS::AppSync::DataSource', {
+      Type: 'NONE',
+      Name: 'ProduceCustom',
+    });
+    expect(ds.name).toBe('ProduceCustom');
+  });
+
   test('appsync configures name and description correctly', () => {
     // WHEN
     api.addNoneDataSource('ds', {
@@ -116,5 +130,3 @@ describe('adding none data source from imported api', () => {
     });
   });
 });
-
-