[Feature]: Add `load_namespaces` and `get_namespaces` to `HDMFIO`

[rly]

What would you like to see added to HDMF?

It's useful in validation to load or get namespaces from an IO object but right now those are implemented per-backend. HDF5IO supports load_namespaces and get_namespaces and ZarrIO supports only load_namespaces. It would be useful if they and any future HDMFIO class supported both of these methods.

cc @stephprince

What solution would you like?

Add load_namespaces and get_namespaces as abstract methods to HDMFIO

Do you have any interest in helping implement the feature?

Yes.

[mavaylon1]

Interesting. Do you have a timeline in mind?

[rly]

Interesting. Do you have a timeline in mind?

This will require some coordination with hdmf-zarr. Let's target July.