Enhance Package Management Pane with Integrated Help and Vignette Display

[Data-Wise]

In Positron, while package management functionalities are present, the help pane currently lacks this level of integration. I propose the following enhancements:

1. Integrated Help Display: When a package is selected in the package management pane, its documentation should automatically appear in the help pane.
2. Vignette Access: Provide a list of available vignettes for the selected package, allowing users to open them directly within the IDE.
3. Search Functionality: Implement a search feature within the help pane to quickly locate functions, datasets, or topics within the selected package.

Benefits:

• Streamlined Workflow: Reduces the need to switch between the IDE and external documentation sources.
• Enhanced Discoverability: Makes it easier for users, especially beginners, to explore and understand package functionalities.
• Consistency with RStudio: Maintains a familiar environment for users transitioning from RStudio to Positron. 

[juliasilge]

I believe we have this tracked in #1369 and more specifically #1369 (comment). Want to take a look and give a 👍 there if you agree?

[ntluong95]

There are at least user-created extensions to work around this, may be you wanna check this