Feat/tool call iteration count parameter

[srebrek]

Allow user to set call LLM/MCP iteration limit to override the hardcoded value.

Example:

await AIHub.Chat()
      .WithModel(Models.OpenAi.Gpt4o)
      .WithMessage("Research the weather in Warsaw, then check forecast for next 3 days")
      .WithTools(new ToolsConfigurationBuilder()
          .AddTool("get_weather", "Get current weather",
              parameters: new { type = "object", properties = new { city = new { type = "string" } } },
              execute: (args) => $"Weather in {args}: sunny, 22°C")
          .WithMaxIterations(3)
          .Build())
      .CompleteAsync();

Do TODO: try to share logic of adding tool to the list across methods