Detailed execution metrics on test runs

WP2 ELIXIR-EXCELERATE benchmarking and technical monitoring team ( @scapella , @jlgelpi , @diglesia , @jmfernandez , @redmitry ) is planning to use planemo to test whether the different versions of bioconda tools with recipes at https://github.com/galaxyproject/tools-iuc are still working.

As we are also interested in the technical benchmarking of the tools, we want to gather metrics like the execution time, used memory, used CPU, etc... We have been talking to @bgruening about this enhancement, and he explained us that it is possible, because Galaxy core already gathers it. So, could you add to the generated JSON all those metrics obtained from each test, please?