Remove default localhost on our uri

modules/aws-http4s/src/smithy4s/aws/AwsClient.scala

@@ -74,7 +74,7 @@ object AwsClient {
           val endpointPrefix = awsService.endpointPrefix.getOrElse(endpoint.id.name)
           val baseUri = HttpUri(
             scheme = HttpUriScheme.Https,
-            host = s"$endpointPrefix.$region.amazonaws.com",
+            host = Some(s"$endpointPrefix.$region.amazonaws.com"),
             port = None,
             path = IndexedSeq.empty,
             queryParams = Map.empty,

modules/bootstrapped/test/src/smithy4s/http/HttpRequestSpec.scala

@@ -28,15 +28,18 @@ final class HttpRequestSpec extends FunSuite {
 
     val uri = HttpUri(
       HttpUriScheme.Https,
-      "example.com",
+      Some("example.com"),
       None,
       IndexedSeq.empty,
       Map.empty,
       None
     )
     val request = HttpRequest(HttpMethod.GET, uri, Map.empty, "")
     val resultUri = writer.write(request, Foo("hello")).uri
-    assertEquals(resultUri, uri.copy(host = "test.hello-other.example.com"))
+    assertEquals(
+      resultUri,
+      uri.copy(host = Some("test.hello-other.example.com"))
+    )
   }
 
 }

modules/core/src/smithy4s/http/HttpRequest.scala

@@ -106,10 +106,10 @@ object HttpRequest {
                 request: HttpRequest[Body],
                 input: I
             ): HttpRequest[Body] = {
-              val hostPrefix = prefixEncoder.write(List.empty, input)
+              val hostPrefix = prefixEncoder.write(List.empty, input).mkString
               val oldUri = request.uri
-              val newUri =
-                oldUri.copy(host = s"${hostPrefix.mkString}${oldUri.host}")
+              val prefixedHost = oldUri.host.map(host => s"$hostPrefix$host")
+              val newUri = oldUri.copy(host = prefixedHost)
               request.copy(uri = newUri)
             }
           }

modules/core/src/smithy4s/http/HttpUri.scala

@@ -18,7 +18,7 @@ package smithy4s.http
 
 final case class HttpUri(
     scheme: HttpUriScheme,
-    host: String,
+    host: Option[String],
     port: Option[Int],
     /**
       * A sequence of URL-decoded URI segment.

modules/http4s-kernel/src/smithy4s/http4s/kernel/package.scala

@@ -65,7 +65,7 @@ package object kernel {
 
     Smithy4sHttpUri(
       uriScheme,
-      uri.host.map(_.renderString).getOrElse("localhost"),
+      uri.host.map(_.renderString),
       uri.port,
       uri.path.segments.map(_.decoded()),
       getQueryParams(uri),
@@ -98,10 +98,10 @@ package object kernel {
 
   def fromSmithy4sHttpUri(uri: Smithy4sHttpUri): Uri = {
     val path = Uri.Path.Root.addSegments(uri.path.map(Uri.Path.Segment(_)).toVector)
-
+    val authority = uri.host.map(h => Uri.Authority(host = Uri.RegName(h), port = uri.port))
     Uri(
       path = path,
-      authority = Some(Uri.Authority(host = Uri.RegName(uri.host), port = uri.port)),
+      authority = authority,
       scheme = Some {
         uri.scheme match {
           case Smithy4sHttpUriScheme.Http  => Uri.Scheme.http

modules/http4s-kernel/test/src/smithy4s/http4s/kernel/Http4sConversionSpec.scala

@@ -118,7 +118,7 @@ object Http4sConversionSpec extends SimpleIOSuite {
   private def aSmithy4sUri(scheme: HttpUriScheme) =
     smithy4s.http.HttpUri(
       scheme = scheme,
-      host = "localhost",
+      host = None,
       port = None,
       path = IndexedSeq.empty,
       queryParams = Map.empty,