Rust: Adjust jump-to-def for paths with generic arguments

[hvitved]

Before

M1::S2::<S>::new(S);
//  ^^^^^^^ -> jump to S2

After

M1::S2::<S>::new(S);
//  ^^ -> jump to S2

[Copilot]

Pull Request Overview

This PR refines jump-to-definition behavior for Rust paths containing generic arguments by adjusting the target location from the entire path segment to just the identifier portion. The change ensures that when users invoke jump-to-definition on paths like M1::S2::<S>::new(S), they navigate to the precise identifier S2 rather than the entire segment including generic arguments.

• Changes the target element for path-based jump-to-definition from PathSegment to NameRef
• Updates the constructor logic to use the segment's identifier instead of the segment itself
• Adds test cases with generic struct definitions and usage to validate the improved behavior

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
rust/ql/test/library-tests/definitions/main.rs	Adds test struct S2<T> with generic parameter and usage example with generic arguments
rust/ql/test/library-tests/definitions/Definitions.expected	Updates expected test results with new definition mappings including generic type references
rust/ql/lib/codeql/rust/internal/Definitions.qll	Modifies PathUse class to target NameRef instead of PathSegment for more precise jump-to-definition

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