Use Files.readString instead of Files.readAllBytes (#5428)

The former avoids creating a copy of byte array,
so it's slightly more performant

Author: geoand

vertx-core/src/main/java/io/vertx/core/impl/HostnameResolver.java

@@ -61,7 +61,7 @@ private static Pattern resolvOption(String regex) {
       File f = new File("/etc/resolv.conf");
       try {
         if (f.exists() && f.isFile()) {
-          String conf = new String(Files.readAllBytes(f.toPath()));
+          String conf = Files.readString(f.toPath());
           int ndotsOption = parseNdotsOptionFromResolvConf(conf);
           if (ndotsOption != -1) {
             ndots = ndotsOption;

vertx-core/src/main/java/io/vertx/core/impl/verticle/JavaSourceContext.java

@@ -67,7 +67,7 @@ public String getClassName() {
    */
   private static String parsePackage(File file) {
     try {
-      String source = new String(Files.readAllBytes(file.toPath()), StandardCharsets.UTF_8);
+      String source = Files.readString(file.toPath());
       // http://stackoverflow.com/questions/1657066/java-regular-expression-finding-comments-in-code
       source = source.replaceAll( "//.*|(\"(?:\\\\[^\"]|\\\\\"|.)*?\")|(?s)/\\*.*?\\*/", "$1 " );
       for (String line : source.split("\\r?\\n")) {