docs: extensions (#1258)

* docs: process docs to include UX Stories requirement

* docs: include note regarding different environments

* Services init

* Remove unused canny logos

* docs: add ModalService diagram

* docs: GIF of notification

* docs: add ui-services page

* docs: simplify ui services call out in the general services docs

* docs: tips and tricks for UI services

* docs: moar pages

* docs: dialog gif

* docs: services in summary/sidebar

* docs: gif examples at top of dialog and notification pages

* docs: add UIModal gif

* docs: details for Dialog Service

* docs: include usage information for ui modal service

* docs: detailed information about our UI Notification Service

* docs: services diagram

* docs: remove unused links

* docs: services example and image

* docs: stubbing extension pages

* docs: UX Stories --> User Cases

* chore: eslint fix

* docs: extensions overview + diagram

* docs: update extensions in sidebar

* docs: extension skeleton and registration info

* docs: copy of maintained extensions table partial in the extensions folder

* docs: swap out old extensions structure for new

docs/latest/services/ui/index.md

@@ -33,7 +33,7 @@ The `ServicesManager` is:
 
 - Passed to the `ExtensionManager`
 - The `ExtensionManager` makes the `ServicesManager` available to:
-  - All of it's lifecycle hooks (`preInit`)
+  - All of it's lifecycle hooks (`preRegistration`)
   - Each "getModuleFunction" (`getToolbarModule`, `getPanelModule`, etc.)
 
 ## Example