Fix GH-9186 @strict-properties can be bypassed using unserialization (#9354)

* Emit deprecation warnings when adding dynamic properties to classes during unserialization - this will become a

Fix GH-9186 @strict-properties can be bypassed using unserialization (#9354)

* Emit deprecation warnings when adding dynamic properties to classes during unserialization - this will become an Error in php 9.0.
(Adding dynamic properties in other contexts was already a deprecation warning - the use case of unserialization was overlooked)
* Throw an error when attempting to add a dynamic property to a `readonly` class when unserializing
* Add new serialization methods `__serialize`/`__unserialize` for SplFixedArray to avoid creating deprecated dynamic
properties that would then be added to the backing fixed-size array
* Don't add named dynamic/declared properties (e.g. $obj->foo) of SplFixedArray to the backing array when unserializing
* Update tests to declare properties or to expect the deprecation warning
* Add news entry

Co-authored-by: Tyson Andre <tysonandre775@hotmail.com>

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Use GC stack in nested data removal

We should be doing this anyway to prevent stack overflow, but on
master this is important for an additional reason: The temporary
GC buffer provid

Use GC stack in nested data removal

We should be doing this anyway to prevent stack overflow, but on
master this is important for an additional reason: The temporary
GC buffer provided for get_gc handlers may get reused if the scan
is performed recursively instead of indirected via the GC stack.

This fixes oss-fuzz #23350.

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