[Feature] Cf Kv batch get request

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Description

The cf kv api support [batch get](https://developers.cloudflare.com/kv/api/read-key-value-pairs/#request-multiple-keys-with-getkeys-string) since [April](https://developers.cloudflare.com/changelog/2025-04-10-kv-bulk-reads/). And it will be really helpful if we supports that.

I think a good api design will be changing this [line](https://github.com/cloudflare/workers-rs/blob/b9ba4d6ef7c877587f68d480ceaa85efac199f91/worker/src/kv/mod.rs#L85)

```rust
pub fn get(&self, name: &str) -> GetOptionsBuilder {
```

to

```rust
pub fn get(&self, name: &[&str]) -> GetOptionsBuilder {
```