JS: Change pruning to not rely on Import

[asgerf]

Background: To ensure MaD library models have a near-zero cost for codebases that don't use the modelled library, we prune models based on what packages are imported in the current codebase. This means we don't parse the access paths or synthesise data flow nodes for irrelevant models.

This means that in order to generate DataFlow::Node, we first have to compute imported paths. There is thus a dependency on the Import class. However, the Import class also depends on local data flow. We therefore have TEarlyStageNode, which is used by Import but does not contain flow summary-generated nodes.

For overlay mode, the TEarlyStageNode has no effect on locality as the entire newtype needs to be made local. The dependency above puts us in an "all or nothing" situation where a lot needs to be made local in order for DataFlow::Node to become local.

In order to simplify the problem, I'm cutting the dependency in this PR, so pruning of flow summaries only depends on an over-approximation, roughly based on what string literals appear in the program.

Note that there are more dependencies to be cut, but I'm trying to split this into small independent PRs.

Evaluation looks neutral.

[Copilot]

Pull Request Overview

This PR changes the pruning mechanism for MaD library models to avoid dependency on the Import class, simplifying the dependency graph for constructing DataFlow::Node. The change replaces precise import path detection with an over-approximation based on string literals to break circular dependencies between imports and data flow analysis.

• Removes dependency on Import class in isPackageUsed predicate
• Uses string literals as an over-approximation for imported packages
• Adds support for string literal type expressions used in dynamic imports

[Copilot]

Using any(JS::Expr imp).getStringValue() will iterate over all expressions in the codebase to find string values, which could be inefficient. Consider using a more specific expression type like JS::StringLiteral to reduce the search space.

Suggested change

	package = any(JS::Expr imp).getStringValue()
	package = any(JS::StringLiteral imp).getStringValue()