ExecutionContext can't be defined

### Problem:
In the latest version type of ExecutionContext was changed from any to unknown.

Before (version 4.20250816.0):
```
interface ExecutionContext {
waitUntil(promise: Promise): void;
passThroughOnException(): void;
props: any;
}
```

After (version 4.20251128.0):
```
interface ExecutionContext {
waitUntil(promise: Promise): void;
passThroughOnException(): void;
readonly exports: Cloudflare.Exports;
readonly props: Props;
}
```

Because of this change our Typescript compiler is complaining that property that we have in context doesn't exist on unknown.

### Proposal:
I am raising a PR where I added option to pass type to ExecutionContext.