Draft: Resolve "Add a Duo Workflow button in VsCode"

Description

As a first iteration to have a button to show workflow instead of just the command menu, we will:

1. Rename the Duo Chat panel to just Duo if the feature flag duo_workflow is enabled
2. Add a button to the top bar of the panel. Clicking on this open workflow.

Related Issues

#1519

How has this been tested?

Screenshots (if appropriate)

What CHANGELOG entry will this MR create?

• fix: Bug fix fixes - a user-facing issue in production - included in changelog
• feature: New feature - a user-facing change which adds functionality - included in changelog
• BREAKING CHANGE: (fix or feature that would cause existing functionality to change) - should bump major version, mentioned in the changelog
• None - other non-user-facing changes

Closes #1519