[chore]: Remove dashboard page.

It doesn't really make a lot of sense to have it here. It just feels a bit cluttered and messy, providing no real extra value to the user.

So, on page load, we will redirect the user to a roadmap that they are currently studying. If they are no, we will take them to a pre-defined roadmap best suited for them.

This will reduce the number of clicks a user needs to make in order to start learning!