WIP: WASM Roy

[ross-spencer]

Following on from the roy optimization last week, I have created a wasm implementation of roy. This PR might be a useful jumping off point for a conversation with most of the work done in pronom_byte_array_helpers.go. In the WASM file we're now able to create a signature file at runtime using embedded defaults. These can also be updated more easily in the future.

I looked at removing the static package and see it's used by github.com/richardlehane/siegfried/pkg/lib but maybe there's another way of improving that API with updated roy work?

Let me know what might need changing, e.g. maybe some of the light duplication in pronom_byte_array_helpers.go can better be done in the existing pronom.go functions?

No rush on my end, I have to move focus onto the workshop this proof of concept is for but will try following up on anything asap.

TODO

• Ensure container signatures work.
• Ensure that if we fork between using a iostream or file that the remainder of the signature loading process does not repeat itself creating redundancy.
• Make sure the new mechanism is compatible with Siegfreid's existing interfaces/API.