Fix IDE integrations for Windows

The verifyNode task only worked on macOS and Linux, and really isn't
necessary anyway. Kill it, and instead just try to run the command. If
it's missing, throw an error.

Also, throw an exception instead of printing the error. This has two
advantages: 1) the error is red and angry and obvious 2) the user can
try again via Android Studio without modifying the gradle.build file

amplify-tools/amplify-tools-gradle-plugin/src/main/groovy/com/amplifyframework/tools/gradle/plugin/AmplifyTools.groovy

@@ -6,44 +6,34 @@ import groovy.json.JsonOutput
 
 class AmplifyTools implements Plugin<Project> {
     void apply(Project project) {
-        def doesNodeExist = true
-        def doesGradleConfigExist
-
         // profile name can be changed in amplify-gradle-config
         def profile = 'default'
         def accessKeyId = null
         def secretAccessKey = null
         def region = null
         def envName = 'amplify'
         def syncEnabled = 'true'
+        def gradleConfigFileName = 'amplify-gradle-config.json'
+
+        project.task('createAmplifyApp') {
+            def npx = 'npx'
+
+            if (project.file(gradleConfigFileName).exists()) {
+                return
+            }
+
+            if (Os.isFamily(Os.FAMILY_WINDOWS)) {
+                npx += '.cmd'
+            }
 
-        project.task('verifyNode') {
             try {
                 project.exec {
-                    commandLine 'npx', '-v'
-                    standardOutput = new ByteArrayOutputStream()
+                    commandLine npx, 'amplify-app', '--platform', 'android'
                 }
             } catch (commandLineFailure) {
-                doesNodeExist = false
-                println("Node is not installed. Visit https://nodejs.org/en/download/ to install it")
-            }
-        }
-
-        project.task('createAmplifyApp') {
-            doesGradleConfigExist = project.file('amplify-gradle-config.json').isFile()
-            if (doesNodeExist && !doesGradleConfigExist) {
-                if (Os.isFamily(Os.FAMILY_WINDOWS)) {
-                    project.exec {
-                        commandLine 'npx.cmd', 'amplify-app', '--platform', 'android'
-                    }
-                } else {
-                    project.exec {
-                        commandLine 'npx', 'amplify-app', '--platform', 'android'
-                    }
-                }
+                throw new Exception('Node.js is not installed. Visit https://nodejs.org/en/download/ to install it.')
             }
         }
-        project.createAmplifyApp.dependsOn('verifyNode')
 
         project.task('getConfig') {
             def inputConfigFile = project.file('amplify-gradle-config.json')