Reduce sizing of homepage content to match designs

Created by: jjinnii

Current implementation of the homepage in VS Code extension matches sourcegraph.com exactly. However, due to the sidebar of VS Code, there is less screen real estate (width), causing the search examples to wrap on a user's default view. (unless they have the sidebar hidden, which users likely will not do)

The designs have a reduced sizing of the homepage content (search examples, Watch & Learn video), icon, etc.).