create JS source maps (#4365)

updated minify plugin to 1.7.6
switch minify plugin to use CLOSURE compiler
enable source map generation https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k
include source maps in distribution files

distribution/adapters/js-adapter-zip/assembly.xml

@@ -30,6 +30,7 @@
             <outputDirectory></outputDirectory>
             <includes>
                 <include>**/*.js</include>
+                <include>**/*.map</include>
                 <include>**/*.d.ts</include>
                 <include>**/*.html</include>
             </includes>

distribution/adapters/js-adapter-zip/pom.xml

@@ -50,7 +50,7 @@
                                     <groupId>org.keycloak</groupId>
                                     <artifactId>keycloak-js-adapter</artifactId>
                                     <outputDirectory>${project.build.directory}/unpacked/js-adapter</outputDirectory>
-                                    <includes>*.js,*.d.ts</includes>                                 
+                                    <includes>*.js,*.map,*.d.ts</includes>
                                 </artifactItem>
                             </artifactItems>
                             <excludes>**/welcome-content/*</excludes>