[FEA] reserve and incremental dump for ScoredHashtable

[jiashuy]

Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. Ex. I wish I could use recsys-examples to do [...]

Describe the solution you'd like A clear and concise description of what you want to happen.

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

Additional context Add any other context, code examples, or references to existing implementations about the feature request here.

---

By submitting this issue, you agree to follow our code of conduct and our contributing guidelines.