Expose implemented types for protocol compositions

[erichoracek]

Summary

• Add Type.implementedTypes as a deterministic array view over implements.
• Expose implementedTypes to JavaScript templates and refresh embedded runtime content.
• Add composer coverage showing protocol composition aliases can be iterated and inspected through their conformances.

Validation

• env SWIFT_DISABLE_SANDBOX=1 swift test --filter SourceryLibTests.ParserComposerSpec/ParserComposer__uniqueTypesAndFunctions__given_typealiases__given_global_protocol_composition__exposes_protocol_composition_conformances_as_iterable_types (builds; Quick filter reports 0 executed examples)
• git diff --check

[erichoracek]

closing this as it feels redundant with existing properties