fix: Use root path when building full destination (#32)

Previously this plugin would not do anything when you put your project's site files under a folder. See the `root` [shared option]. With
this change, the user now can have source files in a folder that is not at the project root.

This may also fix #30, since I am also using Vite 5.x.

[shared option]: https://vitejs.dev/config/shared-options.html

Co-authored-by: Fateh AK <[email protected]>

src/index.ts

@@ -221,7 +221,7 @@ function ViteImageOptimizer(optionsParam: Options = {}): Plugin {
           const handles = files.map(async (publicFilePath: string) => {
             // convert the path to the output folder
             const filePath: string = publicFilePath.replace(publicDir + sep, '');
-            const fullFilePath: string = join(outputPath, filePath);
+            const fullFilePath: string = join(rootConfig.root, outputPath, filePath);
 
             if (fs.existsSync(fullFilePath) === false) return;