Move more of the PackageCollection APIs to native async/await
Motivation:
More modern code that will be able to adopt swift 6 data race safety eventually
Modifications:
PackageMetadataProvider APIs are all now async/await
PackageIndexProtocol APIs are all now async/await
Added question about the need for returning PackageMetadataProviderContext when PackageBasicMetadata can not be read
Move more of the PackageCollection APIs to native async/await
Motivation:
More modern code that will be able to adopt swift 6 data race safety eventually
Modifications:
PackageMetadataProvider APIs are all now async/await PackageIndexProtocol APIs are all now async/await Added question about the need for returning PackageMetadataProviderContext when PackageBasicMetadata can not be read
Result:
More readable code