ProcessWord support UTF-8

modified PorcessWord to working normally for UTF-8 strings and added test cases

Signed-off-by: Daehyeok Mun <daehyeok@gmail.com>
Upstream-commit: bb79b7eb9e1db83fd80121b088aa2e5a4c084ace
Component: engine

components/engine/builder/dockerfile/shell_parser_test.go

@@ -15,7 +15,7 @@ func TestShellParser(t *testing.T) {
 	defer file.Close()
 
 	scanner := bufio.NewScanner(file)
-	envs := []string{"PWD=/home", "SHELL=bash"}
+	envs := []string{"PWD=/home", "SHELL=bash", "KOREAN=한국어"}
 	for scanner.Scan() {
 		line := scanner.Text()