sdk: Add resize feature

[febo]

Problem

As described in anza-xyz/solana-sdk#569, account resize cannot be safely performed using a delta value. Therefore, entrypoints need to store the original data size to reliably track differences. But doing so consume CUs and not every program needs to resize accounts.

Additionally, AccountView::resize was removed since the resize logic is dependent on what the entrypoint does.

Solution

This PR enables account resizing in pinocchio by:

• Adding a "resize" feature to indicate to the entrypoint that the original data size needs to be stored. This consumes 2 CUs per account.
• When the feature is enabled, an impl of the new Resize trait is provided forAccountView, offering resize and resize_unchecked.