Add Custom HTML Configuration for Exporting Reports

[shahbaz-bandits25]

Description: This pull request introduces a new feature to customize HTML configurations for exporting reports in the HTML format. Users can now specify their own HTML header and footer content to be included in the exported HTML file.Like the report content should be on entire HTML page,give styles to particular HTML tag etc.

Changes Made:

Added support for custom HTML header and footer content in the HTML exporter. Updated the export_html function to accept custom HTML configurations. Modified the generate_jasper_report function to allow users to pass custom HTML configurations.