Improvements on Teaclave's performance

[ya0guang]

Motivation & problem statement

In some use cases, Teaclave can be slow and some components needs redesign.

1. For example, when passing a payload to Teaclave's client API, the payload will be transmitted back and forth between several services and this significantly affect its performance when the payload itself is very large. This also happens when the arguments is very large.
2. Another potential improvement is exposing interfaces for unprotected files, or allow users to use raw input files. Sometimes the user may not need to protect all the input files. For example, while conducting genome computing, the reference genome data is from public data set and it needs no protection, but the personal private genome info needs protection. Therefore Teaclave don't need to deal with the decryption of some files.
3. Access control is using FFI and python, and this may not be very performant as using pure Rust.

Proposed solution

1. Redesign the framework and maybe treat the payload as a kind of "input file", therefore alleviate the transmission overhead.
2. Allow unprotected file upload or expose unprotected file interfaces
3. Switch to a logic programming implemented in Rust. miniKanren can be a good choice and it has several Rust implementations. Since Teaclave just needs very simple functions, it can borrow short snippets from these projects or even implement a basic one.

Describe alternatives you've considered

I don't know if there is an alternative solution.

Additional context

The performance of the DB inside Teaclave may also be enhanced.