refactor(image_composition): image::imageops::{overlay -> replace}

* Overlay takes into account the underlying pixel and the overlayed
  pixel to interpolate the final pixel data.

  Eg: This takes effect for transparent regions in PNG images.

* Replace performs the same operation for us but instead it does not
  perform the pixel interpolation and instead just replaces the pixel.

* Test performed on 8-core i5 machine with only 1 `wl_output`:
---
Benchmark 1: ./wayshot-overlay --stdout > /dev/null
  Time (mean ± σ):      81.6 ms ±  14.1 ms    [User: 25.1 ms, System: 17.1 ms]
  Range (min … max):    59.0 ms … 109.8 ms    41 runs

Benchmark 2: ./wayshot-replace --stdout > /dev/null
  Time (mean ± σ):      75.8 ms ±  14.6 ms    [User: 24.7 ms, System: 15.0 ms]
  Range (min … max):    58.2 ms … 105.3 ms    30 runs

Summary
  './wayshot-replace --stdout > /dev/null' ran
    1.08 ± 0.28 times faster than './wayshot-overlay --stdout > /dev/null'
---

Signed-off-by: Shinyzenith <[email protected]>

libwayshot/src/lib.rs

@@ -19,7 +19,7 @@ use std::{
     thread,
 };
 
-use image::{imageops::overlay, RgbaImage};
+use image::{imageops::replace, RgbaImage};
 use memmap2::MmapMut;
 use wayland_client::{
     globals::{registry_queue_init, GlobalList},
@@ -474,7 +474,7 @@ impl WayshotConnection {
                         if let Some(overlayed_image_or_error) = possible_overlayed_image_or_error {
                             if let Ok(mut overlayed_image) = overlayed_image_or_error {
                                 if let Ok(image) = image {
-                                    overlay(&mut overlayed_image, &image, 0, 0);
+                                    replace(&mut overlayed_image, &image, 0, 0);
                                     Some(Ok(overlayed_image))
                                 } else {
                                     Some(image)