Add overload / conversion-precedence test cases

[bryantaustin13]

Summary

Adds library-style tests exercising function-overload resolution and CQL
conversion precedence. Addresses #37.

These use the <library> test format, so this depends on the schema change in
#141 and requires the runner support in cqframework/cql-tests-runner#111 to
execute. It builds on the CqlOverloadMatching.xml file introduced in #61.

Tests added (each a self-contained <library> + one <output name="output">)

Test	Overloads	Call	Expected	Rule
ExactIntegerOverThanConversion	A(Integer), A(Decimal)	A(1)	'IntegerOverload'	exact match beats Integer→Decimal
ImplicitIntegerToDecimal	A(Decimal)	A(1)	'DecimalOverload'	implicit conversion when no exact match
ExactLongOverload	A(Integer), A(Long)	A(1L)	'LongOverload'	exact Long match
ImplicitIntegerToLong	A(Long)	A(1)	'LongOverload'	implicit Integer→Long
ExactDecimalOverQuantity	A(Decimal), A(Quantity)	A(1.0)	'DecimalOverload'	exact match beats Decimal→Quantity
AmbiguousOverload	A(Long), A(Decimal)	A(1)	— (<library invalid="semantic">)	Integer→both ⇒ ambiguous, fails to translate

Expected outputs were validated against the reference CQL engine. Long tests
carry <capability code="system.long"/>. Each library uses a unique name (the
engine caches inline libraries by name+version).

Merge notes

• Base: library-test-support (the Add library-style test support to the test schema #141 schema branch), so the diff here is
  only the test file. Once Add library-style test support to the test schema #141 merges, retarget the base to main.
• Order: merge after Add the overloads test back in #61 so these 6 tests append to its CqlOverloadMatching.xml
  (final file = Add the overloads test back in #61's SimpleOverloadMatching + these 6).
• AmbiguousOverload currently shows as skip in cql-tests-runner, which skips all
  output-less negative tests (pre-existing; tracked separately). The test itself is
  spec-correct and produces the expected ambiguity error against the engine.

Depends on #141 · builds on #61 · addresses #37 · runner: cqframework/cql-tests-runner#111