Merge OpenAiStreamingChatModel and OpenAiChatModel classes

[anunnakian]

Context

This PR fix the issue #954

Change

• I merged the ChatLanguageModel and StreamingChatLanguageModel classes
• I removed the StreamingChatLanguageModel class
• I removed the OpenAiStreamingChatModelBuilderFactory class

Checklist

Before submitting this PR, please check the following points:

• I have added unit and integration tests for my change
• All unit and integration tests in the module I have added/changed are green
• All unit and integration tests in the core and main modules are green
• I have added/updated the documentation
• I have added an example in the examples repo (only for "big" features)
• I have added my new module in the BOM (only when a new module is added)

Checklist for adding new embedding store integration

• I have added a {NameOfIntegration}EmbeddingStoreIT that extends from either EmbeddingStoreIT or EmbeddingStoreWithFilteringIT

[anunnakian]

Hello @LizeRaes, here is my PR that I made during the Devoxx session, please take a look when you have time 🤓

[LizeRaes]

Thanks a lot @anunnakian , nice for streamlining experience! Looking forward to the minor fixes and getting it merged :)

[anunnakian]

Thanks a lot @anunnakian , nice for streamlining experience! Looking forward to the minor fixes and getting it merged :)

Minor changes done :)