Refines workspace repo nodes

Enables panel layout for Commit Graph by default

- updates README
- minor updates to GL+ walkthrough intro

- Adds the Commit Graph
- Adds the Commit Details view

Updates upgrade notification

- adds new images to premium feature sections
- fixes side bar view images to be side-by-side
- in the last step of the getting started walkthrough, add image and a button that links to the premium feature walkthrough
- updates the old settings.png image with a new version
- adds a new image of the quick setup
- adds a note about worktrees not working on the web

Moves generated images into dist/webviews/media

Adds worktree open, create, & delete palette command

Splits path functions into system/paths module