Implement Cast Streaming mirroring, DLNA casting, daemon+GUI, and breadd integration

Builds out the full v1 scope: a vendored+patched openscreen subset for
low-latency Cast Streaming (Mirroring receiver 0F5096E8) alongside the
existing Cast V2/HLS and new DLNA/AVTransport casting paths, breadcastd's
Idle/Casting state machine with a private IPC socket, the breadcast GTK4
popup as a thin IPC client, and bread.cast.*/bread.command.cast.* breadd
integration (device discovery, start/stop, mirroring lifecycle events).
Also adds bakery/systemd/Forgejo CI packaging.

Validated end-to-end against a real Chromecast/Google TV: negotiated
Cast Streaming session, live pipeline playback, and daemon+GUI click-to-cast/
stop through the actual popup.

breadcast-caststream-sys/vendor/openscreen/util/enum_name_table.h

@@ -0,0 +1,51 @@
+// Copyright 2020 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// This file contains helpers for working with enums that require
+// both enum->string and string->enum conversions.
+
+#ifndef UTIL_ENUM_NAME_TABLE_H_
+#define UTIL_ENUM_NAME_TABLE_H_
+
+#include <array>
+#include <string_view>
+#include <utility>
+
+#include "platform/base/error.h"
+#include "util/osp_logging.h"
+#include "util/string_util.h"
+
+namespace openscreen {
+
+inline constexpr char kUnknownEnumError[] = "Enum value not in array";
+
+template <typename Enum, size_t Size>
+using EnumNameTable = std::array<std::pair<const char*, Enum>, Size>;
+
+// Get the name of an enum from the enum value.
+template <typename Enum, size_t Size>
+ErrorOr<const char*> GetEnumName(const EnumNameTable<Enum, Size>& map,
+                                 Enum enum_) {
+  for (auto pair : map) {
+    if (pair.second == enum_) {
+      return pair.first;
+    }
+  }
+  return Error(Error::Code::kParameterInvalid, kUnknownEnumError);
+}
+
+// Get the value of an enum from the enum name.
+template <typename Enum, size_t Size>
+ErrorOr<Enum> GetEnum(const EnumNameTable<Enum, Size>& map,
+                      std::string_view name) {
+  for (auto pair : map) {
+    if (::openscreen::string_util::EqualsIgnoreCase(pair.first, name)) {
+      return pair.second;
+    }
+  }
+  return Error(Error::Code::kParameterInvalid, kUnknownEnumError);
+}
+
+}  // namespace openscreen
+#endif  // UTIL_ENUM_NAME_TABLE_H_