Set profile for rustic-babel block

[132ikl]

Currently, you can only run rustic-babel blocks with the default cargo profile, debug. I was trying to debug an issue that needed ballpark timing estimates, but there was no way to specify --release. It would be nice if you could do :profile 'release, similar to how the :toolchain option works.

[psibi]

I would be happy to accept a PR for the same with a test case.