add structural hint to command examples

[kuhe]

Generate a structural hint instead of only

const command = new StartQueryExecutionCommand(input);

for commands.

Example:

/**
 * const client = new AthenaClient(config);
 * const input = {
 *   QueryString: "STRING_VALUE", // required
 *   ClientRequestToken: "STRING_VALUE",
 *   QueryExecutionContext: {
 *     Database: "STRING_VALUE",
 *     Catalog: "STRING_VALUE",
 *   },
 *   ResultConfiguration: {
 *     OutputLocation: "STRING_VALUE",
 *     EncryptionConfiguration: {
 *       EncryptionOption: "SSE_S3" || "SSE_KMS" || "CSE_KMS", // required
 *       KmsKey: "STRING_VALUE",
 *     },
 *     ExpectedBucketOwner: "STRING_VALUE",
 *     AclConfiguration: {
 *       S3AclOption: "BUCKET_OWNER_FULL_CONTROL", // required
 *     },
 *   },
 *   WorkGroup: "STRING_VALUE",
 *   ExecutionParameters: [
 *     "STRING_VALUE",
 *   ],
 *   ResultReuseConfiguration: {
 *     ResultReuseByAgeConfiguration: {
 *       Enabled: true || false, // required
 *       MaxAgeInMinutes: Number('int'),
 *     },
 *   },
 * };
 * const command = new StartQueryExecutionCommand(input);
 * const response = await client.send(command);
 */

Additional examples diffing the protocol tests for JSv3 can be found in the first commit of aws/aws-sdk-js-v3#4573

[syall]

From the example in the PR description, it looks like commas are missing.

[syall]

This looks great!

Could be refactored to use SimpleCodeWriter for templating and indenting, but not a blocker for this PR.