Redesign low level read/write API

[Xuanwo]

orc-rust tends to expose Arrow's high-level API, but users might want to access Stripe's low-level APIs, for example StripeFactory, Stripe, SchemaMap and so on.

I have submitted some PRs to expose them directly, but I somehow feel it's not a good idea. I suggest redesigning our low-level read/write APIs entirely.