Show progress notification when project is initializing

Proposal

When a new project is being initialized after creating it via the New Project Wizard, the initialization can take a few moments. Initialization can involve creating a new environment, running extension tasks, etc..

If the user doesn't have their Console open, it can look like nothing is happening. It would be better to show a notification that indicates that the new project initialization is in progress and clearly indicate when the tasks are complete.

Relevant Code

I think we should be able to add a notification in src/vs/workbench/services/positronNewProject/common/positronNewProjectService.ts, which shows once NewProjectStartupPhase.CreatingProject starts and indicates that the initialization is done once we get to NewProjectStartupPhase.Complete. We may need to add a phase or otherwise wait just a bit longer for the selected runtime to start.

We can also consider alternative ways to show that the project is being initialized, such as changing the content of the Welcome page.

Start in src/vs/workbench/services/positronNewProject/common/positronNewProjectService.ts and trace the NewProjectStartupPhase.CreatingProject and NewProjectStartupPhase.Complete transitions. Determine how project initialization and runtime startup are reported, then define completion as the point when initialization tasks are finished and the user sees a clear progress and completion notification.