Modify sidebar to be able to have submenus

[Mustafa-Awami]

With this PR you will be able to add submenus to the sidebar

in nav-main.tsx component, you can structure mainNavItems to include sub items like below.

const mainNavItems: NavItem[] = [
        {
            title: 'Dashboard',
            href: dashboard(),
            icon: LayoutGrid,
        },
        {
            title: 'Inquiries',
            icon: Inquiries,
            subItems: [
                {
                    title: 'All Inquiries',
                    href: inquiries.index(),
                },
                {
                    title: 'My Inquiries',
                    href: inquiries.myInquiries(),
                },
            ]
        },
]

This is how the submenu look.

submenu.mp4

[pushpak1300]

Thanks for your pull request!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain this package, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as an additional package so that the community can still take advantage of your contributions!