REST API with raw parameter returns nothing when payload is not UTF-8 encodable

[ohowe1]

Describe the bug

Hi! When calling the REST API to query a node that returns data that cannot be encoded into a UTF-8 string, the REST API returns nothing to the caller. I think it would be expected to return the raw payload, especially when the encoding on Zenoh and the Content-Type are not set to text, or at least to return an error.

This looks to be because the try_to_string is called on the payload bytes here.

zenoh/plugins/zenoh-plugin-rest/src/lib.rs

Lines 222 to 226 in 70820dd

	Ok(sample) => response(
	StatusCode::Ok,
	Cow::from(sample.encoding()).as_ref(),
	&sample.payload().try_to_string().unwrap_or_default(),
	),

To reproduce

1. Start a Zenoh node that responds to some query with non-utf-8 encodable data (ie protobuf)
2. Start the Zenoh router
3. Query through the REST API with the _raw parameter
4. See nothing returned

System info

• Zenoh v1.1.0