Compiled kernel count

[torsteingrindvik]

There should be a way to ask the server how many compiled kernels it has.

A stable application might expect to not JIT more kernels after some time running.
If due to bugs, unsanitized inputs, or other reasons the compile count increases it's good to have a way to check.

By allowing the server to report back to the user how many compiled kernels it currently sits on this can be logged or graphed etc.

Perhaps related: #415