Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/http/cookie/cookie.go

@@ -0,0 +1,52 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package cookie // import "miniflux.app/v2/internal/http/cookie"
+
+import (
+	"net/http"
+	"time"
+)
+
+// Cookie names.
+const (
+	CookieAppSessionID  = "MinifluxAppSessionID"
+	CookieUserSessionID = "MinifluxUserSessionID"
+
+	// Cookie duration in days.
+	cookieDuration = 30
+)
+
+// New creates a new cookie.
+func New(name, value string, isHTTPS bool, path string) *http.Cookie {
+	return &http.Cookie{
+		Name:     name,
+		Value:    value,
+		Path:     basePath(path),
+		Secure:   isHTTPS,
+		HttpOnly: true,
+		Expires:  time.Now().Add(cookieDuration * 24 * time.Hour),
+		SameSite: http.SameSiteLaxMode,
+	}
+}
+
+// Expired returns an expired cookie.
+func Expired(name string, isHTTPS bool, path string) *http.Cookie {
+	return &http.Cookie{
+		Name:     name,
+		Value:    "",
+		Path:     basePath(path),
+		Secure:   isHTTPS,
+		HttpOnly: true,
+		MaxAge:   -1,
+		Expires:  time.Date(1970, 1, 1, 0, 0, 0, 0, time.UTC),
+		SameSite: http.SameSiteLaxMode,
+	}
+}
+
+func basePath(path string) string {
+	if path == "" {
+		return "/"
+	}
+	return path
+}