Add (podman {image,manifest} push --sign-by-sigstore=param-file.yaml)

(podman push) and (podman manifest push) now support --sign-by-sigstore=param-file,
using the containers-sigstore-signing-params.yaml(5) file format.

That notably adds support for Fulcio and Rekor signing.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/github.com/go-openapi/runtime/middleware/not_implemented.go

@@ -0,0 +1,67 @@
+// Copyright 2015 go-swagger maintainers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/go-openapi/runtime"
+)
+
+type errorResp struct {
+	code     int
+	response interface{}
+	headers  http.Header
+}
+
+func (e *errorResp) WriteResponse(rw http.ResponseWriter, producer runtime.Producer) {
+	for k, v := range e.headers {
+		for _, val := range v {
+			rw.Header().Add(k, val)
+		}
+	}
+	if e.code > 0 {
+		rw.WriteHeader(e.code)
+	} else {
+		rw.WriteHeader(http.StatusInternalServerError)
+	}
+	if err := producer.Produce(rw, e.response); err != nil {
+		Logger.Printf("failed to write error response: %v", err)
+	}
+}
+
+// NotImplemented the error response when the response is not implemented
+func NotImplemented(message string) Responder {
+	return Error(http.StatusNotImplemented, message)
+}
+
+// Error creates a generic responder for returning errors, the data will be serialized
+// with the matching producer for the request
+func Error(code int, data interface{}, headers ...http.Header) Responder {
+	var hdr http.Header
+	for _, h := range headers {
+		for k, v := range h {
+			if hdr == nil {
+				hdr = make(http.Header)
+			}
+			hdr[k] = v
+		}
+	}
+	return &errorResp{
+		code:     code,
+		response: data,
+		headers:  hdr,
+	}
+}