Integrate Kepler into Workflows

Description

• Add Kepler as an option to start an Agent session from relevant flows
  • Separated option in quick pick menu to "Start in Kepler"
    • If Kepler is not installed, show a message below the option with a link to "Get Kepler" that navigates to gitkraken.com/kepler
    • If Kepler is installed, this option should use a deeplink to kepler with the relevant context to start the work as a task in Kepler (e.g. repos, associated PRs, issues, etc.)
  • If a default agent is selected, show "Continue with {agent}" as the primary option