Simdify compareDifferentLayouts

[serpent7776]

• compareDifferentLayouts use scalar operations; change it to use vector types
• also change compareSameLayouts to use vector type for x and y coordinates

Locally I didn't notice any performance improvements though, probably because processPixelDifference is still scalar.

The intent was to bring compareSameLayouts and compareDifferentLayouts closer together, but it's not there yet.

[dmtrKovalenko]

I'm worried that we do not actually have test for comparing images of different layout can you please add at least one that you used for your own testing

[serpent7776]

There's at least 2 tests with different layouts, but I can add some additional cases.

• https://github.com/dmtrKovalenko/odiff/blob/main/src/test_core.zig#L43
• https://github.com/dmtrKovalenko/odiff/blob/main/src/test_core.zig#L188

[serpent7776]

I added some more cases. For the new odiff logo test, the number of detected pixels used to be 1209283 for previous odiff version, but is 1209280 now. Does this sound reasonable?