Extract control flow analysis to separate module

Extract a service interface out of ControlFlowInformationProviderImpl
and register its implementation in two "leaf" modules: 'cli',
'idea-core'.

This improves parallel build, since a lot of modules depend on
'frontend' but only these two modules reference the implementation and
thus depend on the full CFA implementation now.

compiler/frontend/cfg/build.gradle.kts

@@ -0,0 +1,15 @@
+plugins {
+    kotlin("jvm")
+    id("jps-compatible")
+}
+
+dependencies {
+    compile(project(":compiler:frontend"))
+    compileOnly(intellijCoreDep()) { includeJars("intellij-core") }
+    compileOnly(intellijDep()) { includeJars("guava", rootProject = rootProject) }
+}
+
+sourceSets {
+    "main" { projectDefault() }
+    "test" {}
+}