Add _from_bytes methods to allow the direct usage of u8 byte arrays

[olliecheng]

Hi, thanks for your work on making this wrapper! This PR adds align_from_bytes and add_alignment_from_bytes versions of the existing AlignmentEngine::align and Graph::add_alignment methods, which take in a &[u8] byte slice instead of a CStr.

[olliecheng]

I believe that this enables better interoperability with other Rust tools and libraries. For instance, bio::io::fastq::Record stores data internally using a non-null terminated byte array. Without this change, one would have to re-allocate the byte array to include a null byte at the end before casting to a CStr, which is redundant, as it seems that spoa doesn't actually use the null byte and instead uses the sequence_len and quality_len values passed into it.