[feature request] multi-format support

I found xq use serde as its deserializer, so it is possible to support other format beside json (yaml for example).

```bash
cat a.yaml | xq --fmt yaml
cat b.data | xq --fmt msgpack
```

and one more step, support schemaless data with additional schema

```bash
cat b.bin | xq --fmt bincode --schema my-bincode-schema.json --schema-fmt json
```
