build: lint code with detekt

[Detekt](https://detekt.dev/) is a linter that is focused on code
issues, whereas ktlint mostly focuses on style. This commit includes
detekt in the Gradle project as an optional feature. No build will fail
atm due to linting errors. We can use this as a hint when developing.

Author: languitar

.detekt.yml

@@ -0,0 +1,12 @@
+style:
+  # handled by ktlint
+  MaxLineLength:
+    active: false
+  ModifierOrder:
+    active: false
+
+  # No need for this
+  ReturnCount:
+    active: false
+  ThrowsCount:
+    active: false

build.gradle.kts

@@ -1,5 +1,6 @@
 import com.github.gradle.node.NodeExtension
 import com.github.gradle.node.NodePlugin
+import io.gitlab.arturbosch.detekt.Detekt
 import kotlinx.html.FlowContent
 import kotlinx.html.a
 import kotlinx.html.body
@@ -44,6 +45,7 @@ plugins {
     alias(libs.plugins.tasktree)
     alias(libs.plugins.dokka)
     alias(libs.plugins.node) apply false
+    alias(libs.plugins.detekt) apply false
 }
 
 group = "org.modelix"
@@ -65,11 +67,14 @@ dependencies {
     dokkaPlugin(libs.dokka.versioning)
 }
 
+val parentProject = project
+
 subprojects {
     val subproject = this
     apply(plugin = "maven-publish")
     apply(plugin = "org.jetbrains.dokka")
     apply(plugin = "org.jlleitschuh.gradle.ktlint")
+    apply(plugin = "io.gitlab.arturbosch.detekt")
 
     version = rootProject.version
     group = rootProject.group
@@ -85,6 +90,22 @@ subprojects {
         version.set("0.50.0")
     }
 
+    tasks.withType<Detekt> {
+        parallel = true
+        // For now, we only use the results here as hints
+        ignoreFailures = true
+
+        buildUponDefaultConfig = true
+        config.setFrom(parentProject.projectDir.resolve(".detekt.yml"))
+
+        reports {
+            sarif.required.set(true)
+            // This is required for the GitHub upload action to easily find all sarif files in a single directory.
+            sarif.outputLocation.set(parentProject.buildDir.resolve("reports/detekt/${project.name}.sarif"))
+            html.required.set(true)
+        }
+    }
+
     val kotlinApiVersion = org.jetbrains.kotlin.gradle.dsl.KotlinVersion.KOTLIN_1_6
     subproject.tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {
         if (!name.lowercase().contains("test")) {

gradle/libs.versions.toml

@@ -17,6 +17,7 @@ tasktree = { id = "com.dorongold.task-tree", version = "2.1.1" }
 modelix-mps-buildtools = { id = "org.modelix.mps.build-tools", version = "1.1.0" }
 dokka = {id = "org.jetbrains.dokka", version = "1.9.0"}
 node = {id = "com.github.node-gradle.node", version = "7.0.1"}
+detekt = { id = "io.gitlab.arturbosch.detekt", version = "1.23.1" }
 
 [versions]
 kotlin = "1.9.10"