Pass `UnwindInfo` in `BootInfo`

It will be nice to pass UnwindInfo in BootInfo so that we can load the kernel ELF in the kernel to do stack unwinding.

#[derive(Debug, Copy, Clone)]
#[repr(C)]
pub struct UnwindInfo {
    /// The base address of the kernel. The kernel base is required
    /// for stack unwinding during kernel panics.
    pub kernel_base: VirtAddr,
    /// The size of the kernel, required to calculate the end of the
    /// kernel base.
    pub kernel_size: usize,

    pub stack_top: VirtAddr,
    pub stack_size: usize
}

Start by tracing how BootInfo is constructed and passed to the kernel, then inspect the kernel ELF loading and stack setup paths. Add UnwindInfo with the specified kernel and stack fields to BootInfo so the kernel receives the data needed for stack unwinding. Done means the information is available in the kernel without breaking existing boot metadata.