add confirm option, if user wants to choose if rehydrate or not

[ZhihaoLau]

This PR adds an optional confirm property. When set, the form state will be rehydrate or not, depends on what boolean value of confirm function being resolve:
usage:

<Persist
        name={formName}
        confirm={async () => {
          const action = await ResolvableMessageBox({
            desc: 'There're unsaved changes since you leave last time, recover?'
          })
          return action === 'confirm';
      }}
/>