Extract module 'config' out of 'frontend'

Also move deprecated TargetPlatform there. This allows to get rid of the
dependency cli.common -> frontend, and even on frontend.common.

compiler/cli/cli-common/build.gradle.kts

@@ -5,7 +5,7 @@ plugins {
 
 dependencies {
     compile(project(":core:util.runtime"))
-    compile(project(":compiler:frontend"))
+    compile(project(":compiler:config"))
     compile(project(":compiler:config.jvm"))
     compile(project(":js:js.config"))
     compileOnly(project(":kotlin-reflect-api"))