Plugin names are not prefixed with the package name

[krassowski]

Something which came up in https://github.com/jupyterlab/jupyterlab/discussions/16082: jupyter-ai plugin names like:

https://github.com/jupyterlab/jupyter-ai/blob/144cc9ba0180c11bce319345666da3b44dad13b7/packages/jupyter-ai/src/index.ts#L29

are not prefixed with the package name:

https://github.com/jupyterlab/jupyter-ai/blob/144cc9ba0180c11bce319345666da3b44dad13b7/packages/jupyter-ai/package.json#L2

Nothing bad in itself, but since users appear to expect jupyter labextension disable @jupyter-ai/core to work maybe it is worth changing to follow the practice used by all other core extensions (and many third party-extensions too).