Make MPSCAsyncChannel source methods nonisolated(nonsending)

`nonisolated(nonsending)` is a 6.2 language feature that allows the inheritance of the callers isolation. The new `MPSCAsyncChannel.Source` send methods should adopt this to avoid unnecessary isolation hops.

Author: FranzBusch

Sources/AsyncAlgorithms/MultiProducerSingleConsumerChannel/MultiProducerSingleConsumerAsyncChannel.swift

@@ -456,7 +456,7 @@ extension MultiProducerSingleConsumerAsyncChannel {
     /// - Parameters:
     ///   - sequence: The elements to send to the channel.
     @inlinable
-    public mutating func send<S>(
+    public mutating nonisolated(nonsending) func send<S>(
       contentsOf sequence: consuming sending S
     ) async throws where Element == S.Element, S: Sequence, Element: Copyable {
       let syncSend: (sending S, inout Self) throws -> SendResult = { try $1.send(contentsOf: $0) }
@@ -493,7 +493,7 @@ extension MultiProducerSingleConsumerAsyncChannel {
     /// - Parameters:
     ///   - element: The element to send to the channel.
     @inlinable
-    public mutating func send(_ element: consuming sending Element) async throws {
+    public mutating nonisolated(nonsending) func send(_ element: consuming sending Element) async throws {
       let syncSend: (consuming sending Element, inout Self) throws -> SendResult = { try $1.send($0) }
       let sendResult = try syncSend(element, &self)
 
@@ -526,7 +526,7 @@ extension MultiProducerSingleConsumerAsyncChannel {
     /// - Parameters:
     ///   - sequence: The elements to send to the channel.
     @inlinable
-    public mutating func send<S>(contentsOf sequence: consuming sending S) async throws
+    public mutating nonisolated(nonsending) func send<S>(contentsOf sequence: consuming sending S) async throws
     where Element == S.Element, S: AsyncSequence, Element: Copyable, S: Sendable, Element: Sendable {
       for try await element in sequence {
         try await self.send(contentsOf: CollectionOfOne(element))