Library extensions

[karthikbhargavan]

This PR does two things.

Library extensions

It adds elements to the F* proof library that were needed in PQ11 and Bertie.
These are yet another motivation for having a complete core library

Operators

It changes the way we compile operators to F*
Currently, all arithmetic operators are translated to the integer operators (+., -., etc.) even if these operators were defined using trait implementations for non-arithmetic types, which results in type errors in F*.
This PR specialized the treatment of booleans and integers, and leaves the rest as typeclass implementations.

This is still not the most general treatment possible, but attempts to do just enough for the examples we have currently.

[maximebuyse]

Looks fine to me. Inserting arithmetic operations symbols only for integers seems like a good change, we will avoid the F* type errors for other types that implement the Rust traits for arithmetic operators.

[franziskuskiefer]

@karthikbhargavan please update and fix ci issues to get this merged

[karthikbhargavan]

This is still not working correctly. Not ready.

[karthikbhargavan]

This one hit some problems with the engine changes. We will try to split apart the library changes to get them in first.