Add benchmarks for compilation

We don’t currently have any benchmarks for the compiler. It would be good to have some. We do want them to run on substantial programs, though, so ideally something that comes out of the plugin.

Fortunately, the plugin saves the (slightly-processed) PIR as well as the final UPLC, so we can do this: get a bunch of programs using the plugin, extract the PIR at runtime and then compile it in the benchmark.