Expose cell-level data validation and type information in pyxlsb

[pranay-sa]

Currently, pyxlsb does not provide access to cell-level data validation rules (such as "Text", "Whole", "Decimal", "Date", etc.) or explicit cell type metadata from XLSB files. This limits the ability of downstream libraries (like pandas) to accurately assign datatypes to cell values based on Excel's data validation settings.

Request:

Add an API to retrieve data validation information for each cell, including the validation type and any constraints.
Expose cell metadata (such as explicit type, format, or validation) in the cell object returned by pyxlsb.
Document the new API and provide usage examples.

Use case:

This feature would allow pandas and other consumers to read XLSB files and assign datatypes to cells based on Excel's intended validation/type, improving fidelity when importing data.