Export a generator API for twsearch

[lgarron]

Right now, experimentalSolveTwsearch(…) outputs up to one solution.
It is possible to get multiple solutions by specifying a min depth, which will randomize the search each time:

cubing.js/src/cubing/search/inside/solve/twsearch.ts

Line 66 in 3992552

setArg("--randomstart");

However, it would be much better to implement a generator API that pulls solutions from C++ → Rust → WASM → JS. It's okay for there to be a bit of extra/redundant work as long as the API is simple to use.