Create converter for nmrML files

This library will then be added in nmr-load-save

The format is open and specifications can easily be find on https://nmrml.org/examples/1/.

For the parsing please use: https://github.com/cheminfo/arraybuffer-xml-parser

There is an example that allows to convert base64 without having to go through the creation of a string

https://github.com/cheminfo/arraybuffer-xml-parser/blob/bdd1f62609f3f151855838d6ad4681eb335f25eb/src/__tests__/base64.test.js#L9-L18

Start with the nmrML examples at nmrml.org/examples/1/ and the arraybuffer-xml-parser base64.test.js example linked in the issue. Define the converter entry point for nmrml-converter and its planned integration with nmr-load-save, then verify that nmrML files can be parsed and their base64 content converted without creating an intermediate string.

Written by the indexing model from the issue text.