Add ChannelOptions to extract base types. (#203)

Motivation:

In some cases users may want to access APIs we haven't exposed
in NIOTransportServices. We should have a fallback that allows users
to do this.

Modifications:

- Add ChannelOptions for getting NWConnection and NWListener.

Result:

Users have an escape hatch

Fix build on non-macOS Apple platforms (#196)

Add new typed async bootstrap APIs back and drop SPI (#191)

* Revert "Back out SPI(AsyncChannel) changes"

This reverts commit 33d2b29.

* Add new typed async bootstrap APIs back and drop SPI

# Motivation
We just merged the removal of the `AsyncChannel` SPI in NIO and can now add back the new APIs in transport services as well.

# Modification
This PR brings back the previous SPI and promotes it to API.

# Result
New typed async bootstraps API for `NIOTransportServices`.

* George review

Add support for UDP clients and servers.

Motivation:

This change was made because UDP support was lacking on iOS. It's needed by my DNS client implementation, which I am in turn using for an iOS app I'm working on relying on SRV typed records.

Modifications:

Adds a NIOTSDatagramListenerBootstrap for making UDP services
Adds a NIOTSDatagramListenerChannel that accepts UDP connections
Adds a NIOTSDatagramChannel for UDP client connections
Adds a NIOTSDatagramBootstrap that can create a new UDP client

Back out SPI(AsyncChannel) changes (#184)

# Motivation
We want to release a new `NIOTS` version without the SPI changes for now.

# Modification
This PR backs out the new `NIOAsyncChannel` APIs.

# Result
No more SPI usage so we can safely release.

Use underscore version of `NIOPreconcurrencySendable` to silence warn…

…ing (#173)

### Motivation
`swift-nio` has deprecated `NIOPreconcurrencySendable` in `2.51.0`. Removing the protocol conformance would be an API breaking change. Keeping the conformance is low cost and not worth the risk.

### Changes
- replace `NIOPreconcurrencySendable` with underscore version `_NIOPreconcurrencySendable`

### Result
We compile again with the latest `swift-nio` release without warnings

Fix documentation and add infrastructure for CI-ing it (#169)

* Fix documentation and add infrastructure for CI-ing it

* Add 2023 to soundness

Allow retrieval of metadata from `NWConnection` (#163)

* Allow retrieval of metadata for a specific protocol from the underlying `NWConnection`

* Address review comments

* Address review comment

* Add availability annotation to tests

* Rename `NIOTSChannelIsNotATransportServicesChannel ` to `NIOTSChannelIsNotANIOTSConnectionChannel `

Add missing availability annotation to NIOTSConnectionBootstrap (#160)

Motivation:

- NIOTSConnectionBootstrap was extended to be marked as non-Sendable,
  this extenion missed the availability annotations.

Modifications:

- Add appropriate availability annotation

Result:

Resolves #159

Replace Lock with NIOLock (#157)

Motivation:

Lock has been deprecated in favour of NIOLock. Warnings aren't great.

Modifications:

- Replace Lock with NIOLock
- Update the minimum required NIO version to 2.42.0.

Result:

Everything builds cleanly