Introducing "Script item" (backend)

With the introduction of JS preprocessing users get the ultimate preprocessing options. With the inclusion of HTTP requests into JS, this provides great options for data collection.

The problem is that there is no proper way to use JS for data collection. This leads to the creation of "hack items". Some generic item like "agent.ping" is created and preprocessing is added to it just to make use of the options available in JS.

It looks like this is the time when "Script item" should be introduced. Script item would execute JS script just like it is done in preprocessing.

Benefits of such a solution:

1. Additional monitoring option.
2. No need to introduce "hackish" items just to use JS.
3. Covers cases when HTTP agent monitoring is requiring multiple steps or complex logic.