aws-lambda: introduce `Function.addSchedule()` integration with EventBridge Scheduler

### Describe the feature

Currently, you need to write the following code to invoke a function on a schedule:

```ts
import { join } from "path";
import {
Schedule,
ScheduleExpression,
} from "@aws-cdk/aws-scheduler-alpha";
import { LambdaInvoke } from "@aws-cdk/aws-scheduler-targets-alpha";
import { Duration, Stack, StackProps } from "aws-cdk-lib";
import { Architecture, LoggingFormat, Runtime } from "aws-cdk-lib/aws-lambda";
import { NodejsFunction } from "aws-cdk-lib/aws-lambda-nodejs";
import { Construct } from "constructs";

export class MyStack extends Stack {
constructor(scope: Construct, id: string, props: StackProps = {}) {
super(scope, id, props);

const cronFunction = new NodejsFunction(this, `CronFunction`, {
functionName: `cron-function`,
entry: join(__dirname, "..", "functions", "cron", "index.ts"),
runtime: Runtime.NODEJS_22_X,
architecture: Architecture.ARM_64,
memorySize: 1024,
timeout: Duration.minutes(1),
loggingFormat: LoggingFormat.JSON,
});

new Schedule(this, "RateBasedSchedule", {
scheduleName: "rate-based-schedule",
schedule: ScheduleExpression.rate(Duration.minutes(1)),
target: new LambdaInvoke(cronFunction),
});
}
}
```

### Use Case

The code could be optimized by introducing a native integration between AWS Lambda and EventBridge Scheduler.

### Proposed Solution

```ts
import { join } from "path";
import { ScheduleExpression } from "@aws-cdk/aws-scheduler-alpha";
import { Duration, Stack, StackProps } from "aws-cdk-lib";
import { Architecture, LoggingFormat, Runtime } from "aws-cdk-lib/aws-lambda";
import { NodejsFunction } from "aws-cdk-lib/aws-lambda-nodejs";
import { Construct } from "constructs";

export class MyStack extends Stack {
constructor(scope: Construct, id: string, props: StackProps = {}) {
super(scope, id, props);

const cronFunction = new NodejsFunction(this, `CronFunction`, {
functionName: `cron-function`,
entry: join(__dirname, "..", "functions", "cron", "index.ts"),
runtime: Runtime.NODEJS_22_X,
architecture: Architecture.ARM_64,
memorySize: 1024,
timeout: Duration.minutes(1),
loggingFormat: LoggingFormat.JSON,
});

cronFunction.addSchedule({
schedule: ScheduleExpression.rate(Duration.minutes(1)),
});
}
}
```

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.170.0

### Environment details (OS name and version, etc.)

Ubuntu 24.04 LTS

Begin at the proposed cronFunction.addSchedule entry point and compare the current Schedule/LambdaInvoke usage shown in the issue. Confirm that the native integration supports the stated rate expression and equivalent scheduled Lambda invocation behavior; done means the proposed API works for this use case.

Written by the indexing model from the issue text.