refactor: Decouple prompt template manager from their users (#115)

This makes it possible to test the user classes

llmcore/IPromptProvider.hpp

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2025 Povilas Kanapickas <povilas@radix.lt>
+ *
+ * This file is part of QodeAssist.
+ *
+ * QodeAssist is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * QodeAssist is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with QodeAssist. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "PromptTemplate.hpp"
+#include <QString>
+
+namespace QodeAssist::LLMCore {
+
+class IPromptProvider
+{
+public:
+    virtual ~IPromptProvider() = default;
+
+    virtual PromptTemplate *getTemplateByName(const QString &templateName) const = 0;
+
+    virtual QStringList templatesNames() const = 0;
+
+    virtual QStringList getTemplatesForProvider(ProviderID id) const = 0;
+};
+
+} // namespace QodeAssist::LLMCore