feat(lambda-events): add Default implementations for all event

[46ki75]

📬 Issue #, if available:

• [lambda-events] Make sure that we have Default implemented for all event types #1009

✍️ Description of changes:

This pull request adds Default implementations for all Lambda event types.

Some event structs derive Default using #[derive(Default)], while others require a manual impl Default to ensure proper initialization.

Note: A few unrelated files were also modified automatically by running cargo clippy --fix. (6137344)

🔏 By submitting this pull request

• I confirm that I've ran cargo +nightly fmt.
• I confirm that I've ran cargo clippy --fix.
• I confirm that I've made a best effort attempt to update all relevant documentation.
• I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ghost]

Hi, thank you for the PR. Looks good to me!