Splits App into AppBase & AppWithConfigBase for impl of new webviews

Adds bundle analyzer
Adds circular deps analyzer
Switches to es2018 output
Removes many circular dependencies

Updates GitLens logo
Adds CodeStream sponsor

https://github.com/dominictarr/event-stream/issues/116

https://github.com/dominictarr/event-stream/issues/116

Keeps all path manipulation on the host rather than guest
Fixes shared/local path munging for mac/windows
Keeps current user lookup local when a guest
Keeps difftool lookup local when a guest
Avoids fetch date lookup when a guest
Stops clearing node_modules (for now)

Enables source maps always
Minifies css
Removes unused plugins

Switches to use full source-map for better debugging (stepping)

Adds the gitlens icon to settings editor and welcome page