Add Sourcegraph graphql API (or use GitHub REST API?)

[bogdan0083]

Github GraphQL is fine but it still doesn't have the ability to search for code. It also doesn't support getting all entryTrees recursively.

On the other hand Sourcegraph graphql API has all those issues fixed and works fine on https://github1s.com/. We can use it as an addition to bring the following features:

• Search not just for repos but also for code fragments
• Repo Page: Render side entries as a hierarchical list with collapsing nodes. Like this: https://mui.com/material-ui/react-tree-view/
• Potentially bring LSP features for source code, like Go To Definition or Find References