gh-107758: Improvements to lltrace feature (#107757)

- The `dump_stack()` method could call a `__repr__` method implemented in Python,
  causing (infinite) recursion.
  I rewrote it to only print out the values for some fundamental types (`int`, `str`, etc.);
  for everything else it just prints `<type_name @ 0xdeadbeef>`.

- The lltrace-like feature for uops wrote to `stderr`, while the one in `ceval.c` writes to `stdout`;
  I changed the uops to write to stdout as well.

Python/optimizer.c

@@ -391,7 +391,7 @@ translate_bytecode_to_trace(
 
 #ifdef Py_DEBUG
 #define DPRINTF(level, ...) \
-    if (lltrace >= (level)) { fprintf(stderr, __VA_ARGS__); }
+    if (lltrace >= (level)) { printf(__VA_ARGS__); }
 #else
 #define DPRINTF(level, ...)
 #endif