Describe the bug
PromptyKernelExtensions.CreateFunctionFromPromptyFile calls PromptyKernelExtensions..CreateFunctionFromPrompty which calls KernelFunctionPrompty.ToPromptTemplateConfig which then calls Prompty.Load.
The path to the prompty file is not passed in the call to Prompty.Load, this means that paths in any ${file:..} references in the prompty file are evaluated relative to the application's working directory rather than to the directory containing the prompty file. This behaviour is different from that when running using the VS Code extension.

To Reproduce

• Create a prompty file containing a ${file:...} reference, e.g.

model:
  api: chat
  configuration:
    type: azure_openai_beta
  parameters:
    response_format: ${file:MySchema.json}

• Save the file in a sub-directory of the application's working directory, e.g. /prompts
• Place the referenced file, e.g. MySchema.json in the sub-directory
• Create a function using .CreateFunctionFromPromptyFile:

  IFileProvider fileProvider = new PhysicalFileProvider(Path.Join(Directory.GetCurrentDirectory(), "prompts"));
  var function = kernel.CreateFunctionFromPromptyFile("my_template.prompty", fileProvider);

• See that the schema file is not loaded.

Expected behavior
${file:...} paths are evaluated relative to the prompty file location.