feat: Add Bedrock API key support (#951)

Author: jbelkins

Sources/SmithyIdentityAPI/Context/Context+AuthSchemePreference.swift

@@ -16,6 +16,12 @@ extension Context {
     public func getAuthSchemePreference() -> [String]? {
         get(key: authSchemePreferenceKey)
     }
+
+    /// The auth scheme preferences for authenticating this request.
+    public var authSchemePreference: [String]? {
+        get { getAuthSchemePreference() }
+        set { set(key: authSchemePreferenceKey, value: newValue) }
+    }
 }
 
 extension ContextBuilder {

Sources/SmithyIdentityAPI/Context/Context+IdentityResolver.swift

@@ -14,6 +14,12 @@ extension Context {
     public func getIdentityResolvers() -> Attributes? {
         get(key: identityResolversKey)
     }
+
+    public func addIdentityResolver<T: IdentityResolver>(value: T, schemeID: String) {
+        var identityResolvers: Attributes = get(key: identityResolversKey) ?? Attributes()
+        identityResolvers.set(key: AttributeKey<any IdentityResolver>(name: schemeID), value: value)
+        set(key: identityResolversKey, value: identityResolvers)
+    }
 }
 
 extension ContextBuilder {

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/HTTPBindingProtocolGenerator.kt

@@ -440,6 +440,7 @@ abstract class HTTPBindingProtocolGenerator(
             operationMiddleware.appendMiddleware(operation, RetryMiddleware(ctx.model, ctx.symbolProvider, retryErrorInfoProviderSymbol))
             operationMiddleware.appendMiddleware(operation, SignerMiddleware(ctx.model, ctx.symbolProvider))
             addProtocolSpecificMiddleware(ctx, operation)
+            addServiceSpecificMiddleware(ctx, operation)
             operationMiddleware.appendMiddleware(operation, AuthSchemeMiddleware(ctx.model, ctx.symbolProvider))
             for (integration in ctx.integrations) {
                 integration.customizeMiddleware(ctx, operation, operationMiddleware)
@@ -482,6 +483,13 @@ abstract class HTTPBindingProtocolGenerator(
         operation: OperationShape,
     )
 
+    protected open fun addServiceSpecificMiddleware(
+        ctx: ProtocolGenerator.GenerationContext,
+        operation: OperationShape,
+    ) {
+        // No operation.  Override in subclasses to install per-service custom middleware/interceptors.
+    }
+
     protected abstract fun addUserAgentMiddleware(
         ctx: ProtocolGenerator.GenerationContext,
         operation: OperationShape,