VSCE: Automate release
Created by: abeatrix
Close https://github.com/sourcegraph/sourcegraph/issues/26437
Combining this with the changes made in the PR for adding the nightly build for VSCE https://github.com/sourcegraph/sourcegraph/pull/34522 to close https://github.com/sourcegraph/sourcegraph/issues/34205.
This PR automates the release process for the VS Cod, where making commits to the vsce/release
branch would trigger the release command to build and publish the extension directly to the VS Code Marketplace.
After the PRs is merged to main, we will need to configure the jobs in buildkite and add the Personal Access Token for VS Code Marketplace into the pipeline.
Test plan
TBC