Fix new EH hang on DebugBreak (#112640)

* Fix new EH hang on DebugBreak

The new exception handling doesn't work well with the DebugBreak in some
cases. E.g. when it is invoked from FATAL_GC_ERROR. The new EH attempts
to handle the STATUS_BREAKPOINT stemming from the DebugBreak, allocate a
managed exception object and hangs since it cannot do that when the GC
is running.

The cause is a missing check for the breakpoint exception in the
ProcessCLRExceptionNew that is present in the old ProcessCLRException.
To fix it, I've copied that code to the ProcessCLRExceptionNew.

Close #112599

* Never process breakpoints via the new EH

src/coreclr/vm/exceptionhandling.cpp

@@ -946,6 +946,14 @@ ProcessCLRExceptionNew(IN     PEXCEPTION_RECORD   pExceptionRecord,
 #ifndef HOST_UNIX
     if (!(pExceptionRecord->ExceptionFlags & EXCEPTION_UNWINDING))
     {
+        // If the exception is a breakpoint, let it go. The managed exception handling
+        // doesn't process breakpoints.
+        if ((pExceptionRecord->ExceptionCode == STATUS_BREAKPOINT) ||
+            (pExceptionRecord->ExceptionCode == STATUS_SINGLE_STEP))
+        {
+            return ExceptionContinueSearch;
+        }
+
         // Failfast if exception indicates corrupted process state
         if (IsProcessCorruptedStateException(pExceptionRecord->ExceptionCode, /* throwable */ NULL))
         {