feat(microservices): add event typings to the `@EventPattern` decorator

[joelday]

Adds overloads for @EventPattern to allow validation that decorated method signatures match event payload types based on a specified mapping type. Includes tests demonstrating correct usage and error cases with // @ts-expect-error.

PR Checklist

Please check if your PR fulfills the following requirements:

• [x] The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• [x] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Adds overloads to the @EventPattern decorator that creates a static type constraint between the pattern and the decorated method's parameter type.

Example:

type FooMessage = {
  foo: string;
};

type BarMessage = {
  bar: number;
};

type EventTypes = {
  'event-pattern-foo': FooMessage;
  'event-pattern-bar': BarMessage;
};

class FooBarTestComponent {
  // correct
  @EventPattern<EventTypes>('event-pattern-bar')
  testBar(event: BarMessage) {}

  // incorrect (foo is specified, but the parameter type is `string` instead of `FooMessage`
  @EventPattern<EventTypes>('event-pattern-foo')
  testFoo(event: string) {}
}

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

• I'm unsure of what documentation should be added/where that lives.
• I'm unsure of whether or not topic is an appropriate name for these overloads instead of metadata.