Missing "topics in" support

[jamesmunns]

We probably need:

• A specific SDK method for topics in listing, like we do for topics out
• a CLI method for listing this (or make sure it's shown somewhere)
• Update the GUI to show this on one of the pages

We do expose this data through the "get schemas" method, but it's not consistent elsewhere:

poststation-util/tools/poststation-sdk/src/lib.rs

Lines 51 to 61 in 8c79ecf

	pub async fn get_device_schemas(&self, serial: u64) -> Result<Option<SchemaReport>, ()> {
	let res = self
	.client
	.send_resp::<GetSchemasEndpoint>(&serial)
	.await
	.map_err(drop)?;
	let Some(res) = res else {
	return Ok(None);
	};
	Ok(Some(res))
	}

[jamesmunns]

Also, we need an example that shows topics in, I don't think we have one in postcard-rpc or poststation.