Added additional tests for ValueLiteralsAndSelectors as suggested by Claude

[bryantaustin13]

Claude's comments about tests not added:
Left empty — deliberately (with reasoning)

• Quantity — the suite serializes quantity literals inconsistently: 5.0 'g'→5.0'g' (no space) in CqlTypesTest's AnyQuantity, but 150.2 '[lb_av]'→150.2 '[lb_av]' (with space) in QuantityTest. Adding a literal-output test would just encode one side of that ambiguity. This is a real finding worth raising before writing tests against it.
• Tuple — round-trip already covered in CqlTypesTest (AnyTuple); exact brace-spacing is fragile.
• Code / Concept / Instance — file marks these "maybe"; Code/Concept selectors need code-system context and have fragile serialization. Left as stubs.