Move Wayland backend to winit-wayland (#4252)

.github/CODEOWNERS

@@ -12,8 +12,7 @@
 /winit-common/src/xkb               @kchibisov
 
 # Wayland
-/src/platform/wayland.rs            @kchibisov
-/src/platform_impl/linux/wayland    @kchibisov
+/winit-wayland                      @kchibisov
 
 # X11
 /src/platform/x11.rs                @kchibisov @notgull

.github/workflows/ci.yml

@@ -194,7 +194,7 @@ jobs:
       run: cargo $CMD test -p winit-common --features core-foundation --no-run
 
     - name: Test winit Common (XKB)
-      if: contains(matrix.platform.target, 'linux')
+      if: contains(matrix.platform.target, 'linux-gnu')
       run: cargo $CMD test -p winit-common --features xkb,x11,wayland --no-run
 
     - name: Test winit Orbital
@@ -210,6 +210,10 @@ jobs:
       if: contains(matrix.platform.target, 'windows')
       run: cargo $CMD test -p winit-win32 --target=${{ matrix.platform.target }}
 
+    - name: Test winit Wayland
+      if: contains(matrix.platform.target, 'linux-gnu')
+      run: cargo $CMD test -p winit-wayland --target=${{ matrix.platform.target }}
+
     # Test only on Linux x86_64, so we avoid spending unnecessary CI hours.
     - name: Test dpi crate
       if: >