Add missing inference API details

[lcawl]

The inference API details in the following pages are currently missing from the specifications:

• AlibabaCloud Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Alibaba Cloud inference API #4021
• Amazon Bedrock Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Amazon Bedrock inference API #4022
• Anthropic Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Anthropic inference API details #4023
• Azure AI studio Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Azure AI Studio inference API #4020
• Azure OpenAI Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Azure OpenAI inference details #4019
• Cohere Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Cohere inference API details #4025
• EIS Adds PUT EIS inference details #3987
• Elasticsearch Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Elasticsearch inference API details #4024
• Elser Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add ELSER inference API details #4026
• Google AI studio Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Google AI Studio inference details #4027
• Google Vertex aI Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Google Vertex AI inference details #4028
• Huggingface Add more inference API REST specifications elasticsearch#125187, Remove inference API pages docs-content#834, Add Hugging Face inference API details #4029
• JinaAI Add JinaAI inference API details #4030
• Mistral Add Mistral inference details #3997, Remove Mistral inference docs-content#813, Add Mistral inference API elasticsearch#125063
• OpenAI Add OpenAI inference details #3929, Add missing OpenAI and Watsonx inference APIs elasticsearch#124989
• Watsonx Draft Watsonx inference API #3866, Edit links to inference APIs docs-content#671, Add missing OpenAI and Watsonx inference APIs elasticsearch#124989

Per conversation with DevTools team, they suggest accomplishing this by having a specification for each unique endpoint (e.g. PUT _inference/completion/google_ai_studio_completion).

[lcawl]

NOTE: The following PR has changes that will need to wait until we've got the complete set of specifications: elastic/elasticsearch#122638

[lcawl]

I've forked off #4075 for additional details that were unearthed during the PR reviews.