feat: Enhance chat completion with tool calling capabilities

- Added support for tools in ChatCompletionRequest, including tool choice and parallel tool calls.
- Introduced ChatCompletionTool and ChatCompletionFunction classes to define tool specifications.
- Updated ChatMessage to include tool calls and tool call IDs.
- Created ChatToolCall and ChatToolFunction classes for managing tool call details.
- Modified TextCompletionClient to support tool calling.
- Updated Grader and Grader2 classes to handle new tool-related logic.
- Enhanced Agent and AgentTest classes to incorporate tool calling in agent workflows.
- Added tests for tool calling functionality in CachedClientTest and CompletionClientTest.

src/main/java/de/extio/lmlib/client/Completion.java

@@ -1,5 +1,15 @@
 package de.extio.lmlib.client;
 
-public final record Completion(String response, String reasoning, CompletionFinishReason finishReason, CompletionStatistics statistics) {
+import java.util.List;
+
+public final record Completion(String response, String reasoning, CompletionFinishReason finishReason, CompletionStatistics statistics, List<ToolCall> toolCalls) {
+
+	public Completion {
+		toolCalls = toolCalls == null ? List.of() : List.copyOf(toolCalls);
+	}
+
+	public Completion(final String response, final String reasoning, final CompletionFinishReason finishReason, final CompletionStatistics statistics) {
+		this(response, reasoning, finishReason, statistics, List.of());
+	}
 
 }