Add the retrowin32 recipe

recipes/wip/emulators/windows/retrowin32/recipe.toml

+#TODO not compiled or tested
+[source]
+git = "https://github.com/evmar/retrowin32"
+[build]
+template = "custom"
+dependencies = [
+    "sdl2",
+]
+script = """
+package=retrowin32
+"${COOKBOOK_CARGO}" build \
+            --manifest-path "${COOKBOOK_SOURCE}/Cargo.toml" \
+            --package "${package}" \
+            --release
+            --x86-emu
+            --sdl
+        mkdir -pv "${COOKBOOK_STAGE}/usr/bin"
+        cp -v \
+            "target/${TARGET}/release/${package}" \
+            "${COOKBOOK_STAGE}/usr/bin/${package}"
+"""