Add ktlint plugin

buildSrc/src/main/kotlin/be/simplenotes/base.gradle.kts

@@ -6,6 +6,7 @@ plugins {
     java
     kotlin("jvm")
     `java-library`
+    id("org.jlleitschuh.gradle.ktlint")
 }
 
 repositories {
@@ -21,6 +22,7 @@ version = "1.0-SNAPSHOT"
 
 dependencies {
     implementation(kotlin("stdlib-jdk8"))
+    implementation(platform("org.jetbrains.kotlin:kotlin-bom:1.4.10"))
 }
 
 tasks.withType<Test> {