feat: Add spotless code formatter with prettier

Author: timonback

README.md

@@ -26,3 +26,8 @@ The application renders content based on mock data in `src/app/shared/mock`.
 It contains multiple mocks - including the ones from the springwolf-core examples projects.
 
 To update the mock data, run `npm run update-mocks`.
+
+### Code Formatting
+
+The project uses spotless together with prettier for code formatting.
+Using the gradle task `spotlessApply`, the code is reformatted to match the style.

build.gradle

@@ -3,6 +3,7 @@ plugins {
   id 'com.github.node-gradle.node' version '2.2.4'
   id 'signing'
   id 'maven-publish'
+  id "com.diffplug.spotless" version "5.0.0"
 }
 
 group = 'io.github.springwolf'
@@ -16,6 +17,8 @@ node {
 }
 
 npm_run_build {
+  dependsOn spotlessCheck
+
   inputs.files fileTree("src")
   inputs.file 'angular.json'
   inputs.file 'package.json'
@@ -124,3 +127,15 @@ publishing {
     }
   }
 }
+
+spotless {
+  encoding 'UTF-8'
+
+  format 'Angular', {
+    target 'src/**/*.ts', 'src/**/*.css', 'src/**/*.html'
+
+    trimTrailingWhitespace()
+    endWithNewline()
+    prettier().config(["singleQuote": true])
+  }
+}