allow different endpoing/sigv4 service names

This seems silly, but I guess in AWS it is a thing that these two values may
be different. Consumers of awshttp have the option of ignoring this, which
should be correct most of the time. Aws.zig will, however, use the service
metadata to do the right thing

src/aws.zig

@@ -6,7 +6,10 @@ const servicemodel = @import("servicemodel.zig");
 
 const log = std.log.scoped(.aws);
 
-pub const Options = awshttp.Options;
+pub const Options = struct {
+    region: []const u8 = "aws-global",
+    dualstack: bool = false,
+};
 
 pub const services = servicemodel.services;
 
@@ -39,7 +42,16 @@ pub const Aws = struct {
         log.debug("service sigv4 name {s}", .{service.sigv4_name});
         log.debug("version {s}", .{service.version});
         log.debug("action {s}", .{action.action_name});
-        const response = try self.aws_http.callApi(action_info.service, service.version, action.action_name, options);
+        const response = try self.aws_http.callApi(
+            service.endpoint_prefix,
+            service.version,
+            action.action_name,
+            .{
+                .region = options.region,
+                .dualstack = options.dualstack,
+                .sigv4_service_name = service.sigv4_name,
+            },
+        );
         defer response.deinit();
         // TODO: Check status code for badness
         var stream = json.TokenStream.init(response.body);

src/awshttp.zig

@@ -67,9 +67,10 @@ pub const AwsError = error{
 pub const Options = struct {
     region: []const u8 = "aws-global",
     dualstack: bool = false,
+    sigv4_service_name: ?[]const u8 = null,
 };
 
-pub const SigningOptions = struct {
+const SigningOptions = struct {
     region: []const u8 = "aws-global",
     service: []const u8,
 };
@@ -240,7 +241,7 @@ pub const AwsHttp = struct {
         httplog.debug("Calling {s}.{s}, endpoint {s}", .{ service, action, endpoint.uri });
         const signing_options: SigningOptions = .{
             .region = options.region,
-            .service = service,
+            .service = if (options.sigv4_service_name) |name| name else service,
         };
         return try self.makeRequest(endpoint, "POST", "/", body, signing_options);
     }