Deprecate arbitrary exceptions in deserialization

[wyfo]

Currently, validators/constructors/converters can raise arbitrary exceptions, which are then converted to ValidationError.
This is a security concern, as it could leak implementation details if unwanted exceptions are not properly catched — let's imagine a validator using database, and leaking connection information if this one is temporarily unreachable. This behavior must be deprecated.

Deprecation should also act as breaking change, with a simple way to get back the old behavior, for example a settings key with a deprecation warning.

However, raising a ValidationError is not convenient today, because it's constructor doesn't accept a simple error message string. Constructor should therefore be overloaded.

Also, validators could take a new parameter describing exceptions allowed to be raised in the validator, which would be then converted to ValidationError.

[wyfo]

Deprecation should also act as breaking change, with a simple way to get back the old behavior, for example a settings key with a deprecation warning.

Finally, no simple way has been added, this is a complete breaking change.

Also, validators could take a new parameter describing exceptions allowed to be raised in the validator, which would be then converted to ValidationError.

As written in the documentation, this completely useless, because a simple decorator can do the job.