custom cell type or custom kernel with custom notebook

### Problem

* when using cell magic extensions, I have to load extension then configure cell magic with parameters on each cell or using config cell magic

### Proposed Solution

* I would like to add a new custom cell type for an existing cell magic
* I would like to add a new cell type item on drop down list
* [nice to have] for the custom cell type parameters or config, I would like to use property inspector to configure per cell config by add that cell magic's parameters and values
* [nice to have] for notebook wide config, I would like to add settings editor

### Additional context

* example custom extension for custom cell type would be https://github.com/ploomber/jupysql for `sql` cell type
* example custom kernel that executes scala by default https://github.com/adtech-labs/spylon-kernel

Start by reviewing the linked JupyterSQL custom cell type and Spylon kernel examples, then compare how JupyterLab extensions expose notebook cell types, kernels, property inspectors, and settings editors. A complete implementation would define the supported extension points and provide the requested custom cell type, dropdown entry, and configuration behavior.

Written by the indexing model from the issue text.