Feat: darkmode icon and funtionality added to the export html page

[gbengaoluwadahunsi]

Contribution: Dark Mode Functionality Added to Export Page Summary This pull request introduces dark mode functionality to the Export page, providing users with the option to switch between dark and light modes seamlessly.

Motivation The motivation behind this change is to enhance user experience on the Export page by offering a dark mode option. Dark mode reduces eye strain and provides a comfortable viewing experience, particularly in low-light environments. By adding this feature, we aim to cater to diverse user preferences and improve overall usability.

Testing Extensive testing has been conducted to ensure the smooth integration of dark mode functionality. This includes testing the toggle switch across different browsers and devices to ensure consistent behavior and appearance. Additionally, user feedback has been gathered to validate the effectiveness of the dark mode feature and ensure it meets user expectations.