[K/N][build] Composite build with build.tools-conventions plugin

Adds convention plugin instead of sources inclusion
inside the buildSrc, effectively reducing the amount
of the code to be compiled in buildSrc.

Merge-request: KT-MR-8898

kotlin-native/endorsedLibraries/kotlinx.cli/build.gradle.kts

@@ -11,7 +11,8 @@ extra["org.jetbrains.kotlin.native.home"] = konanHome
 
 plugins {
     kotlin("multiplatform")
-    konan
+    id("kotlin.native.build-tools-conventions")
+    id("konan")
 }
 
 kotlin {