Implement `conf["viur.paramFilterFunction"]` more efficiently

[phorward]

Maybe with an @property like

viur-core/src/viur/core/config.py

Lines 717 to 747 in 80b9319

	@property
	def tasks_custom_environment_handler(self) -> t.Optional["CustomEnvironmentHandler"]:
	"""
	Preserve additional environment in deferred tasks.
	If set, it must be an instance of CustomEnvironmentHandler
	for serializing/restoring environment data.
	"""
	return self._tasks_custom_environment_handler
	@tasks_custom_environment_handler.setter
	def tasks_custom_environment_handler(self, value: "CustomEnvironmentHandler") -> None:
	from .tasks import CustomEnvironmentHandler
	if isinstance(value, CustomEnvironmentHandler) or value is None:
	self._tasks_custom_environment_handler = value
	elif isinstance(value, tuple):
	if len(value) != 2:
	raise ValueError(f"Expected a (serialize_env_func, restore_env_func) pair")
	warnings.warn(
	f"tuple is deprecated, please provide a CustomEnvironmentHandler object!",
	DeprecationWarning, stacklevel=2,
	)
	# Construct an CustomEnvironmentHandler class on the fly to be backward compatible
	cls = type("ProjectCustomEnvironmentHandler", (CustomEnvironmentHandler,),
	# serialize and restore will be bound methods.
	# Therefore, consume the self argument with lambda.
	{"serialize": lambda self: value[0](),
	"restore": lambda self, obj: value[1](obj)})
	self._tasks_custom_environment_handler = cls()
	else:
	raise ValueError(f"Invalid type {type(value)}. Expected a CustomEnvironmentHandler object.")

In the longer term, we could also look to validate the values in setattr against the type hints.

Originally posted by @sveneberth in #1106 (comment)