[bs-120] Support for groovy templates

* Added GroovyTemplate.template() utility and static import in webapp CLI, so

        @RequestMapping("/")
        @ResponseBody
        String home(Model model) {
           template "home.html", model
        }

    renders the template in /templates/home.html

[Fixes #49832753]

spring-bootstrap-cli/pom.xml

@@ -86,6 +86,11 @@
 			<groupId>org.codehaus.groovy</groupId>
 			<artifactId>groovy</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.codehaus.groovy</groupId>
+			<artifactId>groovy-templates</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.ivy</groupId>
 			<artifactId>ivy</artifactId>