dont' hardcode curves in the benchmarks (!99)

up until now, elliptic curves have been hardcoded in the benchmarks, forcing to run them on all supported curves...

this MR makes it possible to use only a subset of curves.

>  **Note**  
> when running the same commands from !104, minus the "inbreeding" ones which are not affected by this MR, the time goes from 12min 33sec to 4min 28sec  


## TODO
- [x] setup
- [x] commit
- [x] recoding
- [x] fec
- [ ] linalg
- [ ] setup size
- [ ] field operations
- [ ] group operations

>  **Note**  
> because all the unticked bullet points above are far from critical to the paper and do require to measure all curves, i won't change these for now