Unsound usages of unsafe implementation from `u8` to `$t`

[llooFlashooll]

Title: Unsound usages of unsafe implementation from u8 to $t

Hi, I am scanning the clickhouse-srv in the latest version with my own static analyzer tool.

Unsafe conversion found at: src/types/column/iter/mod.rs#L60

   unsafe {
      let mut ptr: *const u8 = ptr::null();
      let mut size: usize = 0;
      column.get_internal(&[&mut ptr, &mut size as *mut usize as *mut *const u8], 0)?;
      assert_ne!(ptr, ptr::null());
      Ok(slice::from_raw_parts(ptr as *const $t, size).iter())
   }

This unsound implementation would create a misalignment issues if the type size of u8 is smaller than the type size of $t.

This would potentially cause undefined behaviors in Rust. If we further manipulate the problematic converted types, it would potentially lead to different consequences such as access out-of-bound. I am reporting this issue for your attention.