proxy: add dedicated Proxy dialog and preferences fields

- New ProxyDialog (Tools > Proxy Settings..., plus 'Proxy Settings...'
  in the project panel and timeline Proxy submenus) unifying global
  proxy settings, per-footage custom presets, generation and deletion
  in one place instead of three scattered entry points; this also fixes
  the Tools menu action opening the wrong preferences tab
- Preferences Disk tab gains an 'include audio in proxies' checkbox and
  an ffmpeg executable path field (blank = auto-detect)
- Add ProxyDialog smoke tests

tests/gtest/CMakeLists.txt

@@ -45,6 +45,7 @@ add_executable(olive-gtest
   viewer_display_repro_test.cpp
   project_serializer_test.cpp
   proxy_manager_test.cpp
+  proxy_dialog_test.cpp
   timeline_marker_test.cpp
   undo_stack_test.cpp
   plugin_support_test.cpp

tests/gtest/proxy_dialog_test.cpp

@@ -0,0 +1,72 @@
+#include <gtest/gtest.h>
+
+#include "config/config.h"
+#include "dialog/proxy/proxydialog.h"
+#include "node/project/footage/footage.h"
+
+namespace
+{
+
+QVariant ProxyDialogConfigValue(const char *key)
+{
+	return olive::Config::Current()[QString::fromUtf8(key)];
+}
+
+} // namespace
+
+TEST(ProxyDialog, ConstructsInGlobalModeWithNullParent)
+{
+	olive::ProxyDialog dialog(nullptr);
+
+	// The global settings editors must reflect the current config values
+	EXPECT_EQ(dialog.ProxyWidth(),
+			  ProxyDialogConfigValue("ProxyWidth").value<int>());
+	EXPECT_EQ(dialog.ProxyHeight(),
+			  ProxyDialogConfigValue("ProxyHeight").value<int>());
+	EXPECT_EQ(dialog.ProxyCRF(),
+			  ProxyDialogConfigValue("ProxyCRF").value<int>());
+	EXPECT_EQ(dialog.ProxyPreset(),
+			  ProxyDialogConfigValue("ProxyPreset").toString());
+	EXPECT_EQ(dialog.ProxyIncludeAudio(),
+			  ProxyDialogConfigValue("ProxyIncludeAudio").toBool());
+	EXPECT_EQ(dialog.FFmpegPath(),
+			  ProxyDialogConfigValue("FFmpegPath").toString());
+}
+
+TEST(ProxyDialog, ConstructsWithFootageList)
+{
+	olive::Footage footage;
+	const QVector<olive::Footage *> items = { &footage };
+
+	olive::ProxyDialog dialog(nullptr, items);
+	SUCCEED();
+}
+
+TEST(ProxyDialog, AcceptSavesGlobalSettingsToConfig)
+{
+	const int old_width = ProxyDialogConfigValue("ProxyWidth").value<int>();
+	const bool old_include_audio =
+		ProxyDialogConfigValue("ProxyIncludeAudio").toBool();
+	const QString old_ffmpeg_path =
+		ProxyDialogConfigValue("FFmpegPath").toString();
+
+	{
+		olive::ProxyDialog dialog(nullptr);
+		dialog.SetProxyWidth(640);
+		dialog.SetProxyIncludeAudio(!old_include_audio);
+		dialog.SetFFmpegPath(QStringLiteral("/tmp/oak-test-ffmpeg"));
+		dialog.accept();
+	}
+
+	EXPECT_EQ(ProxyDialogConfigValue("ProxyWidth").value<int>(), 640);
+	EXPECT_EQ(ProxyDialogConfigValue("ProxyIncludeAudio").toBool(),
+			  !old_include_audio);
+	EXPECT_EQ(ProxyDialogConfigValue("FFmpegPath").toString(),
+			  QStringLiteral("/tmp/oak-test-ffmpeg"));
+
+	// Restore previous config values so other tests are unaffected
+	olive::Config::Current()[QStringLiteral("ProxyWidth")] = old_width;
+	olive::Config::Current()[QStringLiteral("ProxyIncludeAudio")] =
+		old_include_audio;
+	olive::Config::Current()[QStringLiteral("FFmpegPath")] = old_ffmpeg_path;
+}