SwiftNIO 2.65.0

Important changes to the NIOFileSystem module

The NIOFileSystem module has been renamed _NIOFileSystem to make it more
obvious that it isn't yet stable API.

The existing NIOFileSystem module currently re-exports _NIOFileSystem and will
be removed in the next minor release. You should update your imports accordingly
to avoid being broken by the next release.

SemVer Minor

• Add NIOBSDSocket.Option for SO_BROADCAST (#2678)
• Add delegate for collecting EventLoop tick metrics (#2608)
• Raise minimum Swift version to 5.8 (#2675)
• Expose NIOThreadPool.numberOfThreads publicly. (#2676)
• Prevent BufferedWriter from producing empty files (#2677)
• Change BufferedReader.read(while:) signature (#2688)
• Added file and line to NIOAsyncWriterError description (#2693)
• Add a helper for setting or cascading optional promises (#2697)
• Underscore the NIOFileSystem module (#2683, #2689)

SemVer Patch

• Add cancellation to NIOThreadPool's async runIfActive (#2679)
• Handle 'atomically' created files more gracefully when detached (#2682)
• Remove DispatchGroup and replace with condvar (#2687)
• Use NIOThreadPool in NIOFileSystem (#2692)
• Add privacy manifest (#2695)
• Retain a ref to NIOAsyncWriter until channel active (#2703)

Other Changes

• Clarify Client/Server column headers (#2691, patch credit to @davedelong)
• Add support for SWIFTCI_USE_LOCAL_DEPS convention (#2699)
• Update issue template link in SECURITY.md (#2680)
• Remove temp directories after tests (#2690)
• Tolerate IPv6 address resolution failure (#2704)