Function `get_frame_content_size`

fn get_frame_content_size(src: &[u8]) -> Result<Option<u64>, ContentSizeError>

Wraps the ZSTD_getFrameContentSize() function.

Args:

src: A prefix of the compressed frame. It should at least include the frame header.

Returns:

Err(ContentSizeError) if src is too small of a prefix, or if it appears corrupted.
Ok(None) if the frame does not include a content size.
Ok(Some(content_size_in_bytes)) otherwise.