ENH: Add Sonic Visualizer annotation format

[NickleDave]

https://www.sonicvisualiser.org

an implementation here: https://github.com/shyamblast/Koogu/blob/master/koogu/data/annotations/sonicvisualiser.py

A complication is that there are both 1-D "regions" and 2-D "boxes" https://www.sonicvisualiser.org/doc/reference/4.5/en/#regions https://www.sonicvisualiser.org/doc/reference/4.5/en/#boxes Separate classes for each?

[NickleDave]

An example dataset here https://zenodo.org/records/7997739

[NickleDave]

Code to parse xml here in pykanto, be sure to cite: https://github.com/nilomr/pykanto/blob/3ecaeb9747720d19afa10d1183112d06ea721680/pykanto/utils/custom.py#L32