Get rid of kotlinx-coroutines usage in scripting libs and plugins

the dependency on the coroutines library caused various problems like
KT-30778, or stdlib/runtime version conflicts.
The only function used was `runBlocking`, so this change replaces it
with the internal implementation based on the similar internal thing
from the stdlib.
#KT-30778 fixed

libraries/scripting/common/build.gradle.kts

@@ -7,7 +7,6 @@ project.updateJvmTarget("1.6")
 
 dependencies {
     compile(kotlinStdlib())
-    compile(commonDep("org.jetbrains.kotlinx", "kotlinx-coroutines-core"))
     compileOnly(project(":kotlin-reflect-api"))
     testCompile(commonDep("junit"))
 }