vsce: fix build and add workspace recommendations

Created by: abeatrix

Closes https://github.com/sourcegraph/sourcegraph/issues/34829 & https://github.com/sourcegraph/sourcegraph/issues/36137

Issue 1: Broken build on main

Ref: https://github.com/sourcegraph/sourcegraph/issues/36137

The current build is broken on the main branch because of the recent changes in https://github.com/sourcegraph/sourcegraph/pull/35982

From buildkite (the latest build):

Fix

This PR includes fixes for the affected files.

The build from this PR is now passing the integration test:

Issue 2: Add Sourcegraph VSCE to Workspace Recommendations

Ref: https://github.com/sourcegraph/sourcegraph/issues/34829

Demo

Demo	When	Behavior
Loom Video 1	no extension.json file	Show CTA > Yes > Create extension.json file > Add SG to recs list
Loom Video 2	Has extension.json file, but SG not on the list	Show CTA > Yes > Add SG to recs list to existing file
Loom Video 3	When there is an extension.json file, and SG is on the recommendation list	Do not show CTA
Loom Video 4	When extension.json file is empty	Show CTA > Yes > Create extension.json file > Add SG to recs list

Test plan

See loom videos linked above for https://github.com/sourcegraph/sourcegraph/issues/34829

For https://github.com/sourcegraph/sourcegraph/issues/36137, the integration is passing

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.