gh-151613: Fix remote debugging frame cache ABA (#151614)
The remote debugging frame cache previously used only the last_profiled_frame address as its cache anchor. If a frame returned and a later frame reused the same _PyInterpreterFrame address, the profiler could accept a stale cache entry and splice parent frames from a different call chain into the current stack.
This adds a last_profiled_frame_seq counter next to last_profiled_frame, increments it when the anchor advances, stores it in frame cache entries, and validates cache hits against both the frame address and the sequence. Cache miss walks now copy stack chunks before storing new cache entries so stored continuations come from a stable snapshot. The new regression test exercises alternating call chains and checks that cached stacks never contain frames from both branches.
(cherry picked from commit 8cda6ae2f1)
Treat the debug offset tables read from a target process as untrusted input
and validate them before the unwinder uses any reported sizes or offsets.
Add a shared validator in debug_offsets_validation.h and run it once when
_Py_DebugOffsets is loaded and once when AsyncioDebug is loaded. The checks
cover section sizes used for fixed local buffers and every offset that is
later dereferenced against a local buffer or local object view. This keeps
the bounds checks out of the sampling hot path while rejecting malformed
tables up front.
