Make the help dialog box scrollable and switch to using tabs

[ClementTsang]

Describe the feature request

Why should we consider this feature request? Describe why, and/or how you think this feature will solve the issue, or overall improve the application:

EDIT: now two parts:

1. Since help can wrap and entry size can go on for a bit, making it scrollable would solve the issue of potentially overflowing.

2. More of an addendum since we're going to work with the dialog box anyways. tui-rs comes with tabs; we can use that to our advantage instead of our current tab system.

Additional context/details

Provide any additional context or details here. What needs to be done, why, etc:

A good example of how to do the scrolling this is ncdu. The procedure would probably be as follows:

• Add a scroll state to app state. This doesn't have to use the bar system we use on others, we can just read it like a ticker tape (up and down scroll up/down how much is seen regardless, no bar

• Canvas will ofc need to display this somehow. Use arrows to display (and hide if at border).

• May need to play around with canvas widths too in the end.

In regards to tabs, this is more of a side suggestion.

[ClementTsang]

Solved by #127