feat(mm, fs, smp): optimize virtio read/write and support prefetch for anonymous lazy allocation, enable multi-core startup and basic shell support

[li041]

Summary:

• This PR introduces two performance-related improvements in the memory management and filesystem subsystems:

Details:

1. Anonymous mapping prefetch:
   Implements a prefetch mechanism for anonymous lazy allocation during page fault handling.
   When a page fault occurs in a lazily allocated anonymous region, the kernel now prefetches adjacent pages to reduce subsequent faults and improve overall memory access efficiency.

2. VirtIO read/write optimization:
   Optimizes the read/write path in virtio_drivers to avoid unnecessary memory copies between buffers.
   This reduces CPU overhead and improves I/O throughput, especially for large or frequent data transfers.

3. Implements SMP initialization to start secondary CPUs during kernel boot.
   Each secondary CPU runs its own runtime initialization and joins the scheduler, enabling parallel execution of tasks and improved CPU utilization.

[AsakuraMizu]

Nonono plz don't bundle everything into one PR. SMP support should be in a separate PR.

[AsakuraMizu]

See #11 and #12.