feat: Run Script action

[Lacah]

Create a new Flow Designer custom action called “Run Script”, which allows dynamic server-side script execution within flows.

This action should accept a script input (string) that contains arbitrary server-side JavaScript code, execute it, and return its output as an action output.

The purpose of this feature is to give builders and developers a lightweight, reusable utility to run ad-hoc scripts directly in Flow Designer without creating a dedicated Script Action or Script Include. It is particularly useful for rapid prototyping, conditional logic, and development workflows.

[jiteshmalik]

@Lacah This request definitely made me pause and think through some important questions—such as who gets access to this, what privilege level the scripts run at, whether it opens doors for ACL bypasses, and how it aligns with compliance requirements like SOX or PCI-DSS. But honestly, the technical puzzle was interesting enough that I decided to dig into it anyway.

Implementation Challenge:
Turns out ServiceNow's JavaScript APIs make this trickier than expected. The eval() function only works in global scope, and GlideScopedEvaluator (which would be the "proper" scoped option) needs you to save the script to a GlideRecord first before it can run anything. There's no clean way to just execute a script string from memory in a scoped app—you either have to persist it to a table or work in global scope, and both of those options bring their own security headaches.

So I have tried a custom action with a flexible approach that uses a temporary table to handle the GlideScopedEvaluator requirement.

[SapphicFire]

Jitesh has come up with a great solution to this, and I welcome other contributors who would like to introduce their own approaches and implementations. At this stage, I am not comfortable with merging such actions into the repository due to how potentially destructive they are and the commensurate increase in risk they present. However, I am happy to mark such items as hacktoberfest-accepted. Good luck, and happy hacking!