feat(web3.js): expose rpcEndpoint in client for web3.js (#23719)

Adds a getter to the commitment class to expose the rpcEndpoint property.

web3.js/src/connection.ts

@@ -2230,6 +2230,13 @@ export class Connection {
     return this._commitment;
   }
 
+  /**
+   * The RPC endpoint
+   */
+  get rpcEndpoint(): string {
+    return this._rpcEndpoint;
+  }
+
   /**
    * Fetch the balance for the specified public key, return with context
    */