feat(appsync): stabilize appsync module 🎆🎆 🎆 (#23633)

Change stability and maturity of `@aws-cdk/aws-appsync` constructs to stable.

Fixes: #6836

----

### All Submissions:

* [X] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Construct Runtime Dependencies:

* [ ] This PR adds new construct runtime dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-construct-runtime-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: MrArnoldPalmer

packages/@aws-cdk/aws-appsync/README.md

@@ -9,13 +9,7 @@
 >
 > [CFN Resources]: https://docs.aws.amazon.com/cdk/latest/guide/constructs.html#constructs_lib
 
-![cdk-constructs: Experimental](https://img.shields.io/badge/cdk--constructs-experimental-important.svg?style=for-the-badge)
-
-> The APIs of higher level constructs in this module are experimental and under active development.
-> They are subject to non-backward compatible changes or removal in any future version. These are
-> not subject to the [Semantic Versioning](https://semver.org/) model and breaking changes will be
-> announced in the release notes. This means that while you may use them, you may need to update
-> your source code when upgrading to a newer version of this package.
+![cdk-constructs: Stable](https://img.shields.io/badge/cdk--constructs-stable-success.svg?style=for-the-badge)
 
 ---
 

packages/@aws-cdk/aws-appsync/package.json

@@ -136,8 +136,8 @@
       "props-physical-name:@aws-cdk/aws-appsync.AppsyncFunctionProps"
     ]
   },
-  "stability": "experimental",
-  "maturity": "experimental",
+  "stability": "stable",
+  "maturity": "stable",
   "awscdkio": {
     "announce": false
   },