Adding toggle for dark/light mode

[ShaikArshidBanu]

Is your feature request related to a problem? Please describe. It is frustating for the dark mode users to use the website in the light mode.

Describe the solution you'd like In order to improve the usability of the website by both dark & light mode users , a manual toggle option can be provided to switch between the modes.

Describe alternatives you've considered System Preference Sync: Automatically switch modes based on the user's system or device settings.

Additional context Please assign me this issue under GSSOC'24 label.