[stdlib] Set AV to 2.0, LV to 1.9 for main compilations, build tests with K2

libraries/stdlib/common/build.gradle

@@ -37,6 +37,8 @@ compileKotlinCommon {
 
 compileKotlinCommon {
     kotlinOptions {
+        languageVersion = "1.9"
+        apiVersion = "2.0"
         freeCompilerArgs = [
                 "-module-name", project.name,
                 "-opt-in=kotlin.RequiresOptIn",
@@ -44,6 +46,7 @@ compileKotlinCommon {
                 "-opt-in=kotlin.contracts.ExperimentalContracts",
                 "-Xallow-kotlin-package",
                 "-Xexpect-actual-classes",
+                "-Xsuppress-api-version-greater-than-language-version-error",
         ]
     }
 }