CI Deployment to Visual Studio Marketplace

[bmingles]

#18 setup Azure DevOps configuration needed to publish the vscode extension to the Visual Studio Marketplace. It is currently only setup for specific users to use personal access tokens to deploy. We want to setup automated deployments via CI / CD pipeline.

• Create a service user account in our Azure DevOps org https://dev.azure.com/deephaven-oss/ . Not sure how things like MFA work for such an account.
• Figure out strategy for updating access tokens
• CI / CD deployment config (likely Github actions)/

Note: There is apparently a REST API that can be used to manage personal access tokens. Not sure if this would work for use or not, but here's a reference to the FAQ https://learn.microsoft.com/en-us/azure/devops/organizations/accounts/manage-personal-access-tokens-via-api?view=azure-devops#faq