Add option to set exportFormat from Column builder.

[yajra]

This PR will allow setting of Excel's column format via Column builder definition:

Column::make('mobile')->exportFormat('00000000000'),
Column::make('total')->exportFormat(NumberFormat::FORMAT_CURRENCY_EUR_SIMPLE),

Ref: https://docs.laravel-excel.com/3.1/exports/column-formatting.html

The PR will also auto-detect date fields 😍

Column::make('report_date')->exportFormat('mm/dd/yyyy'),
Column::make('created_at'),
Column::make('updated_at')->exportFormat(NumberFormat::FORMAT_DATE_DATETIME),