[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/build-tools/gradle.properties

@@ -0,0 +1,14 @@
+cacheRedirectorEnabled=true
+bootstrap.kotlin.default.version=1.8.20-dev-5197
+kotlin.build.gradlePlugin.version=0.0.39
+
+org.gradle.java.installations.fromEnv=\
+  JDK_1_6,JDK_16,\
+  JDK_1_7,JDK_17,\
+  JDK_1_8,JDK_18,\
+  JDK_9_0,JDK_9,\
+  JDK_10_0,JDK_10,\
+  JDK_11_0,JDK_11,\
+  JDK_15_0,JDK_15,\
+  JDK_16_0,\
+  JDK_17_0