BREAKING CHANGE: The function's usage remains the same, only the name
was changed.

Before:
```ts
import { defineSignal, setListener, condition } from '@temporalio/workflow';
import { unblockSignal } from './definitions';

export const unblockSignal = defineSignal('unblock');

export async function myWorkflow() {
  let isBlocked = true;
  setListener(unblockSignal, () => void (isBlocked = false));
  await condition(() => !isBlocked);
}
```

After:
```ts
import { defineSignal, setHandler, condition } from '@temporalio/workflow';
import { unblockSignal } from './definitions';

export const unblockSignal = defineSignal('unblock');

export async function myWorkflow() {
  let isBlocked = true;
  setHandler(unblockSignal, () => void (isBlocked = false));
  await condition(() => !isBlocked);
}
```