HackStudio: Allow customizing the actions of the Build & Run buttons

This commit introduces per-project settings that can be customized
through a JSON file placed in '.hackstudio/config.json' in the
project's root

Userland/DevTools/HackStudio/ProjectConfig.cpp

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2022, the SerenityOS developers.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "ProjectConfig.h"
+#include <AK/NonnullOwnPtr.h>
+#include <LibCore/File.h>
+
+namespace HackStudio {
+
+ProjectConfig::ProjectConfig(JsonObject config)
+    : m_config(move(config))
+{
+}
+
+ErrorOr<NonnullOwnPtr<ProjectConfig>> ProjectConfig::try_load_project_config(String path)
+{
+    auto file = TRY(Core::File::open(path, Core::OpenMode::ReadOnly));
+    auto file_contents = file->read_all();
+    file->close();
+
+    auto json = TRY(JsonValue::from_string(StringView { file_contents }));
+    if (!json.is_object())
+        return Error::from_string_literal("The topmost JSON element is not an object");
+
+    return adopt_own(*new ProjectConfig(json.as_object()));
+}
+
+NonnullOwnPtr<ProjectConfig> ProjectConfig::create_empty()
+{
+    JsonObject empty {};
+    return adopt_own(*new ProjectConfig(empty));
+}
+
+Optional<String> ProjectConfig::read_key(String key_name) const
+{
+    auto const& value = m_config.get(key_name);
+    if (!value.is_string())
+        return {};
+
+    return { value.as_string() };
+}
+
+}