Cellarr

- slrum runner's manifest now accepts an additional key: "sbatch_extra_args", to add any additional SBATCH headers to the generated scripts.

- 'config' is renamed to 'context_or_config' to accept both TileDB's context or config objects. This supports in-memory TileDB contexts from [Phil](https://github.com/hanslovsky) [[#79](https://github.com/TileOme/cellarr/pull/79)].
- Fixes the condition for path to assay groups.
- Supports querying of dense arrays with the `CellArrDataset` class.

- Support csc matrices in layers, although not common ran into a situation where the anndata object was stored from R.

- Construct cellarr TileDB files on HPC environments based on slurm
(reference: [61](https://github.com/cellarr/cellarr/pull/61))

- chore: Remove Python 3.8 (EOL).
- precommit: Replace docformatter with ruff's formatter.

- Functionality to iterate over samples and cells.
- Explicitly mention that slicing defaults to TileB's behavior, inclusive of upper bounds.