Fix erroneous .unwrap()

[matheus23]

Summary

An .unwrap() in the PrivateFile implementation can panic, if the blockstore doesn't contain the blocks to read the file.

Solution

We should just propagate out the result in this function:

rs-wnfs/wnfs/src/private/file.rs

Lines 387 to 400 in d77d335

	pub async fn get_content(
	&self,
	forest: &PrivateForest,
	store: &impl BlockStore,
	) -> Result<Vec<u8>> {
	let mut content = Vec::with_capacity(self.get_content_size_upper_bound());
	self.stream_content(0, forest, store)
	.for_each(|chunk| {
	content.extend_from_slice(&chunk.unwrap());
	future::ready(())
	})
	.await;
	Ok(content)
	}

There's TryStreamExt. It may have some functions to do this.