Incorrect return type for ActiveRecord encrypted hashes

Bit of an edge case, but:

class MyModel < ApplicationRecord
  serialize :secret_hash, type:Hash, coder: JSON
  encrypts :secret_hash
end

results in the following signatures:

class MyModel
    sig { returns(::String) }
    def secret_hash; end

    sig { params(value: ::String).returns(::String) }
    def secret_hash=(value); end
end

which makes sense since secret_hash is a string in the DB schema (due to being encrypted), but the type for the accessors should be T::Hash[T.untyped, T.untyped].

I can take a stab at a PR if this is something that would be accepted into Tapioca.

Start by reproducing the MyModel example and inspecting the generated RBI signatures for the encrypted serialized hash. Trace how Tapioca derives accessor types from serialize and encrypts; done when both accessors use T::Hash[T.untyped, T.untyped] and the relevant behavior is covered by tests.