Use ML completion extension point from 193 platform

- completion-ranking-kotlin jar used to be in the IDEA itself; thanks to new extension it can reside in the plugin from now on
- ML completion is turned off by default
- use `implementation` dependency because `completion-ranking-kotlin` is required during runtime

idea/build.gradle.kts

@@ -5,6 +5,7 @@ plugins {
 
 repositories {
     maven("https://jetbrains.bintray.com/markdown")
+    maven("https://jetbrains.bintray.com/intellij-third-party-dependencies")
 }
 
 sourceSets {
@@ -103,6 +104,10 @@ dependencies {
         testRuntime(intellijPluginDep("java"))
     }
 
+    Platform[193].orHigher {
+        implementation(commonDep("org.jetbrains.intellij.deps.completion", "completion-ranking-kotlin"))
+    }
+
     compileOnly(commonDep("org.jetbrains", "markdown"))
     compileOnly(commonDep("com.google.code.findbugs", "jsr305"))
     compileOnly(intellijPluginDep("IntelliLang"))