New highlighting/line markers/diagnostics test infrastructure

The current test framework has a number of shortcomings, such as
different markups for different kinds, those formats can not be
mixed in one test file, lacks composability, re-use of it is complicated
This commit contains the first version of the new test runner
to which tests will be migrated in the future.

compiler/frontend/src/org/jetbrains/kotlin/checkers/utils/CheckerTestUtil.kt

@@ -62,7 +62,7 @@ object CheckerTestUtil {
     private const val IGNORE_DIAGNOSTIC_PARAMETER = "IGNORE"
     private const val INDIVIDUAL_DIAGNOSTIC = """(\w+;)?(\w+:)?(\w+)(?:\(((?:".*?")(?:,\s*".*?")*)\))?"""
 
-    internal val rangeStartOrEndPattern = Pattern.compile("(<!$INDIVIDUAL_DIAGNOSTIC(,\\s*$INDIVIDUAL_DIAGNOSTIC)*!>)|(<!>)")
+    val rangeStartOrEndPattern = Pattern.compile("(<!$INDIVIDUAL_DIAGNOSTIC(,\\s*$INDIVIDUAL_DIAGNOSTIC)*!>)|(<!>)")
     val individualDiagnosticPattern: Pattern = Pattern.compile(INDIVIDUAL_DIAGNOSTIC)
 
     fun getDiagnosticsIncludingSyntaxErrors(