[Refactor] Update controllers' CRUD functions in example packages

[jannyHou]

Description

A follow up story of #2654
After implementing the new decorator @requestBody(spec, model, options) in #3496, update the example packages, apply the new annotation to controller CRUD methods.

Acceptance Criteria

• Update the templates in @loopback/cli to adopt the new annotation.
• Upgrade examples to provide the descriptive configs(model, options) using the new @requestBody() decorator.

[stale]

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[stale]

This issue has been closed due to continued inactivity. Thank you for your understanding. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository.