Prefer `ptr.add([usize])` over `ptr.offset([usize] as isize)`

[frewsxcv]

Checklist

• Prefer ptr.add([usize]) over ptr.offset([usize] as isize)
• Prefer ptr.sub([usize]) over ptr.offset(-([usize] as isize))
• Prefer ptr.wrapping_add([usize]) over ptr.wrapping_offset([usize] as isize)
• Prefer ptr.wrapping_sub([usize]) over ptr.wrapping_offset(-([usize] as isize))

API links

• https://doc.rust-lang.org/std/primitive.pointer.html#method.add
• https://doc.rust-lang.org/std/primitive.pointer.html#method.offset