Add support for better search tools in docs

[AbhijithGanesh]

Algolia search

The current full-text search supported by Sphinx really misses out on edge cases, I have brought this up on the discourse thread: https://discourse.ros.org/t/growing-issue-with-ros-documentation/36075

I feel we could use the Algolia search to improvize the same

Update

Algolia is closed-source, proprietary AI tool, we need better FOSS alternatives

[kscottz]

If you are going to request a feature you need to at least point to the tool you propose we use. My cursory Google search indicates that Algolia is a proprietary AI search tool that costs approximately $0.40 per 1000 searches. We have around 100,000 visitors a month. How do you propose we pay for this?

[AbhijithGanesh]

I have renamed the issue to "better search" so that we could navigate through all open-source solutions that fit in our issue

[ros-discourse]

This issue has been mentioned on ROS Discourse. There might be relevant details there:

https://discourse.ros.org/t/improving-search-for-ros-docs-technical/36153/1

[AbhijithGanesh]

@kscottz we need to decide how to move with this! I've marked my solutions in the thread, all of them will need considerable moving of the docs to a new framework