FEAT: spec compliannce - allow reading non compressed flatbuffers

[ianhi]

Per spec flatbuffers have either ZStd or None compression.

icechunk/icechunk-format/src/lib.rs

Lines 492 to 499 in fcee571

	/// Compression algorithm used for metadata files.
	#[repr(u8)]
	#[derive(Debug, Clone, Copy, PartialEq, Eq)]
	pub enum CompressionAlgorithmBin {
	None = 0u8,
	Zstd = 1u8,
	}

but currently we only support writing and reading. zstd

icechunk/icechunk/src/asset_manager.rs

Lines 1195 to 1205 in fcee571

	async fn check_and_decompress(
	mut read: Pin<Box<dyn AsyncBufRead + Send>>,
	file_type: FileTypeBin,
	) -> RepositoryResult<(SpecVersionBin, Vec<u8>)> {
	let (spec_version, compression) = check_header(&mut read, file_type).await?;
	debug_assert_eq!(compression, CompressionAlgorithmBin::Zstd);
	let mut decoder = ZstdDecoder::new(read);
	let mut buffer = Vec::new();
	decoder.read_to_end(&mut buffer).await.capture()?;
	buffer.shrink_to_fit();
	Ok((spec_version, buffer))

at a minimum we need to support reading