Fix generated summary docs for convenience HashMap / Vec members

[rcoh]

Previously the docs said Vec<String> when the method actually accepted String, similarly for HashMap.

Motivation and Context

• DescribeImagesFluentBuilder's image_ids function does not take a Vec<String> as the docs say awslabs/aws-sdk-rust#825

Description

Fix the generator to be aware of Vec/Hashmap methods

Testing

• UT
• audit codegen diff

Checklist

• I have updated CHANGELOG.next.toml if I made changes to the AWS SDK, generated SDK code, or SDK runtime crates

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[Velfi]

ty for adding a test too

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• Client Test (ignoring whitespace)
• No codegen difference in the Server Test
• Server Test Python (ignoring whitespace)
• No codegen difference in the Server Test Typescript

A new doc preview is ready to view.