Add Openai FT samples

[PratibhaShrivastav18]

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[nick863]

Please provide the implementation for GetFineTuningClients method.

[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

Azure.AI.Projects
Azure.AI.Projects.OpenAI

[nick863]

We need to move this note to the markdown file and provide the snippet of WaitForFileProcessingAsync .
```C# Snippet:AI_Projects_FineTuning_WaitForFileProcessingHelper
```

Does this code work like shown above if we will just run it? Will the file be in the FileStatus.Processed state?

[nick863]

Let us add the WaitForFileProcessing for all sample to make sure that the sample is always passing.

[PratibhaShrivastav18]

The equivalent .cs files do include the WaitForFileProcessing helper and always pass. The .md files are meant to document and I think this should convey the idea. Let's keep it this way, unless you think otherwise

[nick863]

We need to demonstrate the right practice for customer. The problem is that the code above may fail without ensuring that UploadFile has actually uploaded the file. We still have the section about File Processing, saying the WaitForFileProcessing needs to present in the production code. Lat us add WaitForFileProcessing in each sample to make sure that customer understands, what should be done. Our goal is that customer can copy our sample code and use it in production.

[nick863]

We need to demonstrate the right practice for customer. The problem is that the code above may fail without ensuring that UploadFile has actually uploaded the file. We still have the section about File Processing, saying the WaitForFileProcessing needs to present in the production code. Lat us add WaitForFileProcessing in each sample to make sure that customer understands, what should be done. Our goal is that customer can copy our sample code and use it in production.