[NEW FEATURE TEST]: add test cases and edge case coverage for inlay hints and code lens

[harshanacz]

Overview

Two new features were added in branch feat/inlay-hints-and-code-lens:

• getInlayHints() — shows attribute type and required markers inline
• getCodeLens() — shows "N references" above named elements

This issue tracks writing test cases and verifying edge case behavior for both.

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Inlay Hints — getInlayHints()

Happy path

• Attribute with a non-string XSD type (e.g. xs:boolean) → produces : boolean type hint
• Attribute marked use="required" in schema → produces * parameter hint
• Both hints appear together on the same attribute when type is non-string and required

Edge cases

• Attribute with xs:string type → no hint produced (skip rule)
• Attribute with no type defined in schema → no hint produced
• Attribute with no value (<el attr />) → valueEnd is undefined, must not crash
• Element not found in schema → returns []
• No schema provider passed → returns []
• Range filter: hints outside the given range are excluded
• Range filter: hints inside the given range are included

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Code Lens — getCodeLens()

Happy path

• Named element with 2+ references → "N references" (plural)
• All reference attributes are counted: key, ref, target, href, type, base

Edge cases

• Named element with 0 references → "0 references"
• Named element with exactly 1 reference → "1 reference" (singular, not "1 references")
• Two elements sharing the same name value → both lenses show the same count
• Element with no name attribute → not included in results
• Empty document → returns []
• Deeply nested named elements → still detected correctly

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Files to add tests in

• src/services/xmlInlayHints.test.ts
• src/services/xmlCodeLens.test.ts