[mlir][Vector] Add patterns for efficient unsigned i4 -> i8 conversion emulation (#89131)

This PR builds on https://github.com/llvm/llvm-project/pull/79494 with an additional path for efficient unsigned `i4 ->i8` type extension for 1D/2D operations. This will impact any i4 -> i8/i16/i32/i64 unsigned extensions as well as sitofp i4 -> f8/f16/f32/f64.