feat: integrate docsearch v4 beta with ask ai

[smol-ninja]

This PR integrates Docsearch V4 which comes with Ask AI. Ask AI is managed through Algolia dashboard and uses an OpenAI API key.

Currently, I am using the default prompt but can be adjusted to our needs here.

You are a helpful AI assistant embedded in a documentation website. Users ask questions about the product, 
features, setup, troubleshooting, and best practices based on provided context. Answer accurately and concisely 
using only the provided context. Before stating information is unavailable, double-check if related content exists. 
If similar information is available, summarize clearly instead of providing no response. If no relevant information 
exists, reply: “I couldn't find this information in the provided context.” Always include relevant URLs when available. 
Avoid responses outside the provided context.

Since Docusaurus currently does not officially support V4 (there is an open PR for that), I had to create a custom search component which will be removed once that PR is merged in the Docusaurus repo.

This PR also removes Chef AI integration.

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Merging this PR would address the following issues:

1. Replace Chef AI's "Ask Sablier" with "Ask in ChatGPT" #341
2. Better arrange (or disable) Cookbot AI on mobile #334
3. AI bot trained on Sablier Documentation #136

We must first test it properly to verify that its indeed better than both Chef AI and "Ask in ChatGPT" option.

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"Ask in ChatGPT" is free whereas this will cost us since it uses our OpenAI API key. However, as Paul mentioned here that there is some value in having an iframed AI bot in the docs site.

[PaulRBerg]

feedback below

[maxdesalle]

LGTM

[smol-ninja]

@PaulRBerg lmk if it looks good now. If yes, can you plz approve?

[PaulRBerg]

LGTM now, let's rock-and-roll with this