Adds a limit on the number of queries

- adds headings, and moves the majority of text content to the body of each step
- most steps now have a simple, one-line description
- adds "try now" section to premium feature walkthrough with a button to try
- adds and updates content in premium feature introduction step
- removes an unnecessary file

Aligns with other gate messaging states
  Simplifies context keys for premium
Fixes purchase link to point to account site
Polishes other gate messaging

Reduces startup impact

- 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

Adds show method to webview views

Adds Learn about Premium Features to command palette

Adds links footer to home view when welcome is hidden
Polishes welcome/settings page headers
Removes links from welcome page
Removes old welcome view

Adds associated PRs to worktree branches
Adds worktrees to the settings page
Adds unpublished markers to worktrees

Disallows deletes of main worktrees & handles errors if attempted
Disallows skip confirmation of worktree create
Fixes issues with worktree folder location choosing and creation
Forces prompting for worktree location by default

Adds worktree open, create, & delete palette command

For upcoming premium features

Hides unsupported search options

Reworks revision uris to use a packed authority for better stability

Should hopefully no longer be required

Adds new visited paths trie for fast lookup of seen paths (to avoid git calls)
Replaces the tracked cache with a paths trie
All tries are case aware based on os and scheme (if uri based)

Adds new detectNestedRepositories setting to improve performance
Automatically handles nested repos for open document and remaps paths
Reworks isTracked for perf & nested repo detection

Changes excludes to a Set for faster matching
Splits getRepository into get & create (also removes async for get)
Replaces repo path methods with repo versions (part of moving away from string paths)
Renames getRemotes to getRemotesWithProviders & getRemotesCore to getRemotes

Adds unit testing (just for the trie for now)

Consolidates to node-fetch 2.6.7 as Octokit requires v2