Architecture setup for VS Code extension

Created by: jjinnii

Plan

Tracking issue for architecture work being done by @tjkandala . This issue covers:

• Any exploratory work being done on how to expose Search
• Implementation work to switch from current notebook setup to webviews. You can read about that decision here.

Tracked issues

@tjkandala

Completed

• (🏁 252 days ago) https://github.com/sourcegraph/sourcegraph/issues/26445    🏳️ Extensibility 3
• (🏁 127 days ago) https://github.com/sourcegraph/sourcegraph/issues/26448    🏳️ Extensibility 3
• (🏁 127 days ago) https://github.com/sourcegraph/sourcegraph/issues/26440    🏳️ Extensibility 3
• (🏁 127 days ago) https://github.com/sourcegraph/sourcegraph/issues/26438    🏳️ Extensibility 3