Switch kotlin version to 1.9

with appropriate fixes in testdata, tests and other
places.

libraries/tools/kotlin-stdlib-docs/kotlin_big/build.gradle

@@ -7,7 +7,7 @@ final String kotlinRootDir = rootProject.file("../../../").absolutePath.replace(
 final String kotlinLibsDir = "$buildDir/libs"
 
 final String githubRevision = isTeamcityBuild ? project.property("githubRevision") : "master"
-final String kotlinVersion = isTeamcityBuild ? project.property("deployVersion") : "1.8.255-SNAPSHOT"
+final String kotlinVersion = isTeamcityBuild ? project.property("deployVersion") : "1.9.255-SNAPSHOT"
 final String repo = isTeamcityBuild ? project.property("kotlinLibsRepo") : "$kotlinRootDir/build/repo"
 
 println("# Extracting info:")
@@ -95,4 +95,4 @@ project.extensions.uncommentSinceKotlinForNewEnums = {
     }
     file.write(String.join("\n", lines))
   }
-}
+}