feat: finish interceptors migration

Removes all Middleware types, references, and implementations, completing
migration to using Orchestrator + Interceptors. Tests using middleware
were also migrated to use Orchestrator + Interceptors. Codegen was updated,
removing the `useInterceptors` setting, switching all code that was either
generating middleware or interceptors to just generate interceptors. This
also allowed removing some other existing generator code around middleware
steps.

As with the corresponding aws-sdk-swift commit, this is already a large commit
so I wanted to avoid doing too much refactoring or moving code around. For
example, I didn't change file names or type names. There's probably a good
deal of refactoring that can be done, but it is out of scope for this PR.

Also, this commit removes the amz-sdk-invocation-id/amz-sdk-request header impl
as it was moved to aws-sdk-swift in the corresponding commit.

Sources/ClientRuntime/Endpoints/EndpointResolverMiddleware.swift

@@ -13,7 +13,7 @@ import struct SmithyHTTPAuthAPI.SelectedAuthScheme
 import enum SmithyHTTPAuthAPI.SigningAlgorithm
 import enum SmithyHTTPAuthAPI.SigningPropertyKeys
 
-public struct EndpointResolverMiddleware<OperationStackOutput, Params: EndpointsRequestContextProviding>: Middleware {
+public struct EndpointResolverMiddleware<OperationStackOutput, Params: EndpointsRequestContextProviding> {
     public let id: Swift.String = "EndpointResolverMiddleware"
 
     let endpointResolverBlock: (Params) throws -> Endpoint
@@ -31,23 +31,6 @@ public struct EndpointResolverMiddleware<OperationStackOutput, Params: Endpoints
         self.endpointParams = endpointParams
         self.authSchemeResolver = authSchemeResolver
     }
-
-    public func handle<H>(
-        context: Smithy.Context,
-        input: HTTPRequestBuilder,
-        next: H
-    ) async throws -> OperationOutput<OperationStackOutput>
-        where H: Handler,
-              Self.MInput == H.Input,
-              Self.MOutput == H.Output {
-        let selectedAuthScheme = context.selectedAuthScheme
-        let request = input.build()
-        let updatedRequest =
-            try await apply(request: request, selectedAuthScheme: selectedAuthScheme, attributes: context)
-        return try await next.handle(context: context, input: updatedRequest.toBuilder())
-    }
-    public typealias MInput = HTTPRequestBuilder
-    public typealias MOutput = OperationOutput<OperationStackOutput>
 }
 
 extension EndpointResolverMiddleware: ApplyEndpoint {

Sources/ClientRuntime/Idempotency/IdempotencyTokenMiddleware.swift

@@ -7,22 +7,14 @@
 
 import class Smithy.Context
 
-public struct IdempotencyTokenMiddleware<OperationStackInput, OperationStackOutput>: Middleware {
+public struct IdempotencyTokenMiddleware<OperationStackInput, OperationStackOutput> {
     public let id: Swift.String = "IdempotencyTokenMiddleware"
     private let keyPath: WritableKeyPath<OperationStackInput, String?>
 
     public init(keyPath: WritableKeyPath<OperationStackInput, String?>) {
         self.keyPath = keyPath
     }
 
-    public func handle<H>(context: Smithy.Context,
-                          input: MInput,
-                          next: H) async throws -> MOutput
-    where H: Handler, Self.MInput == H.Input, Self.MOutput == H.Output {
-        let withToken = addToken(input: input, attributes: context)
-        return try await next.handle(context: context, input: withToken)
-    }
-
     private func addToken(input: OperationStackInput, attributes: Smithy.Context) -> OperationStackInput {
         var copiedInput = input
         if input[keyPath: keyPath] == nil {
@@ -31,10 +23,6 @@ public struct IdempotencyTokenMiddleware<OperationStackInput, OperationStackOutp
         }
         return copiedInput
     }
-
-    public typealias MInput = OperationStackInput
-    public typealias MOutput = OperationOutput<OperationStackOutput>
-    public typealias Context = Smithy.Context
 }
 
 extension IdempotencyTokenMiddleware: HttpInterceptor {