build: switch to spotless (#355)

* build: switch to spotless

add in some other basic formatting steps that allow for easy
auto-correction

* build: lint text files as well

* chore: remove license headers from package-info files

spotless can't verify these

build-logic/build.gradle.kts

@@ -1,6 +1,6 @@
 plugins {
     `kotlin-dsl`
-    id("org.jlleitschuh.gradle.ktlint")
+    id("com.diffplug.spotless")
 }
 
 repositories {
@@ -15,8 +15,14 @@ dependencies {
     implementation(libs.licenser)
     implementation(libs.gradleKotlinJvm)
     implementation(libs.gradleDokka)
-    implementation(libs.gradleKtlint)
+    implementation(libs.spotless)
 
     // https://github.com/gradle/gradle/issues/15383#issuecomment-779893192
     implementation(files(libs.javaClass.superclass.protectionDomain.codeSource.location))
 }
+
+spotless {
+    kotlin {
+        ktlint()
+    }
+}