bench info added to debugger

Context

Benchmark utilities have their own binary, that run PVM and Fast Exec on a predetermined scenario (kernel + messages). This proposal turn benchmark utilities in a lib, with the binary defined as before separately, and adds a command bench to the debugger, that runs benchmark utils on the current inputs, and outputs some information (nb of kernel_run, nb of non-padding tickes, time).

Manually testing the MR

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR