Introduce repo settings conventions

First convention is to configure Gradle build cache.

buildSrc/settings.gradle

@@ -1,6 +1,13 @@
+import org.gradle.api.internal.GradleInternal
+
 pluginManagement {
     apply from: '../repo/scripts/cache-redirector.settings.gradle.kts'
     apply from: '../repo/scripts/kotlin-bootstrap.settings.gradle.kts'
+
+    if (((GradleInternal) gradle).isRootBuild()) {
+        includeBuild '../repo/gradle-settings-conventions'
+    }
+
     repositories {
         maven { url "https://maven.pkg.jetbrains.space/kotlin/p/kotlin/kotlin-dependencies" }
         mavenCentral()
@@ -8,6 +15,10 @@ pluginManagement {
     }
 }
 
+plugins {
+    id "build-cache"
+}
+
 File versionPropertiesFile = new File(rootProject.projectDir.parentFile, "gradle/versions.properties")
 def versionProperties = new Properties()
 versionPropertiesFile.withInputStream {
@@ -30,16 +41,4 @@ dependencyResolutionManagement {
     }
 }
 
-buildscript {
-    repositories {
-        maven { url "https://maven.pkg.jetbrains.space/kotlin/p/kotlin/kotlin-dependencies" }
-        mavenCentral()
-    }
-
-    def buildGradlePluginVersion = ext["kotlin.build.gradlePlugin.version"]
-    dependencies {
-        classpath("org.jetbrains.kotlin:kotlin-build-gradle-plugin:$buildGradlePluginVersion")
-    }
-}
-
 include "prepare-deps"