First pass at converting "blame" commits into a unified model

Adds changes diff for first commit changes

Since we are using native date formatting the formatter abstraction is no longer needed

Adds app/env to startup logging

Refactors Git static class into an instance (so it could be re-used for vsls)
Reworks vsls guest for better stability

Avoids 'system' imports

Reworks revision uris to use a packed authority for better stability

Need to defer this more, but this should help some

Since microsoft/vscode#3025 is now fixed, file watching works outside the workspace

Ensures known SCM repos are known to GitLens

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

As `.git` is a file, not a directory

Adds unit testing (just for the trie for now)

Cleans up overloads