feat: add lz4 support

[arpankapoor]

This PR adds LZ4 support, drawing from the gzip (encoder) and bzip2 (decoder) implementations.

[NobodyXu]

Thank you!

I have some questions for the PR

[NobodyXu]

Thank you for taking my advice!

For the impl, I think there are some bugs and some rooms for improvements

[NobodyXu]

Suggested change

	let (dst_buffer, dst_max_size) = if direct_output {
	let output_len = output.unwritten().len();
	(output.unwritten_mut(), output_len)
	} else {
	let buffer_size = self.block_buffer_size;
	let buffer = self
	.maybe_buffer
	.get_or_insert_with(|| PartialBuffer::new(Vec::with_capacity(buffer_size)));
	buffer.reset();
	(buffer.unwritten_mut(), buffer_size)
	};
	let (dst_buffer, dst_max_size) = if direct_output {
	let output_len = output.unwritten().len();
	output.unwritten_mut()
	} else {
	let buffer = self
	.maybe_buffer
	.get_or_insert_with(|| PartialBuffer::new(Vec::with_capacity(self.block_buffer_size)));
	buffer.reset();
	buffer.unwritten_mut()
	};
	let dst_max_size = dst_buffer.len();

[NobodyXu]

I'm slightly worried about this unwrap_unchecked, would be good if we can optimize this out the unwrap completely, i.e. by returning another option along side dst_buffer

[NobodyXu]

I'm slightly worried about this unwrap_unchecked, would be good if we can optimize this out the unwrap completely, i.e. by returning another option along side dst_buffer