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

plugins/scripting/scripting-compiler/build.gradle.kts

@@ -35,6 +35,7 @@ dependencies {
     testCompile(commonDep("junit:junit"))
 
     testImplementation(intellijCoreDep()) { includeJars("intellij-core") }
+    testImplementation(commonDep("org.jetbrains.kotlinx", "kotlinx-coroutines-core"))
     testRuntimeOnly(intellijDep()) { includeJars("jps-model", "jna") }
 
     testImplementation(project(":kotlin-reflect"))