Replace all occurrences of WITH_RUNTIME with WITH_STDLIB

We are going to deprecate `WITH_RUNTIME` directive. The main reason
behind this change is that `WITH_STDLIB` directive better describes
its meaning, specifically it will add kotlin stdlib to test's classpath.

compiler/tests-spec/testData/codegen/box/templates/identifiers/variableDeclarationEntry.kt

@@ -1,4 +1,4 @@
-<!DIRECTIVES("WITH_RUNTIME")!>
+<!DIRECTIVES("WITH_STDLIB")!>
 
 val <!ELEMENT(1)!> = {`false`: Boolean -> !`false` }