[Darwin] Change strategy for single pid versus all pids

[NickLaMuro]

Changes:

• Makes helper methods for core pieces of the original .ps method
• Simplifies the action of Sys::ProcTable.ps to be a ternary that choose between two helper methods.

The new flow of this ternary in Sys::ProcTable.ps can be described as follows:

• If the method has a pid passed in, it will call get_info_for_pid, with the pid as the argument (and a block, if there is one)
• If the pid value is nil, then the get_info_for_all_pids method will be called, and get_info_for_pid will be called for each pid that it finds. Block evaluation is the same as it was before, and running with a block won't add the struct to the array.

That said, the changes here have a very minimal impact to performance, if any.

Extracted from https://github.com/djberg96/sys-proctable/pull/65

[djberg96]

@NickLaMuro Any chance you could update this for 1.2.x?

[NickLaMuro]

Yeah, I can take a look at doing this tomorrow, as well as seeing what it would take for the other operating systems.

[NickLaMuro]

@djberg96 Sorry for taking forever to get around to this. I spent a few minutes on this and I think I rebased it properly. That said, I really need to check to be sure, and not sure if the tests cover all cases.

[NickLaMuro]

So... benchmarks are not really showing much of a change with this (if anything, this is making it slower...), so unsure whether it is worth the effort. Will leave it up to you.

[djberg96]

@NickLaMuro Alright, then I will go ahead and close it.