Use WorkspaceFolder instead of URIs in IWorkspaceContextService

configuration contribution point: support for array of settings sections, deprecate the 'allOf' trick used in CSS.

Adopt to use getWorkspaceState instead of hasFolderWorkspace or hasMultiFolderWorkspace

Introduce an API in workspace contet service to check current workspace is with given workspace identifier

* drop workspace ID from workspace file

* make folders types an object instead of just string

* fix compile

* polish relauncher for id change

* migrate old workspace format to new on startup

* more migration from previous workspace id

* more migration code

* change folder format to be a path

* support for relative paths in workspace file

* fix of ctor call

* put root validation and filtering into workspace

* ensure we always have file resources

* fix tests

* add tests for workspace

* 💄

* linting

- Provide folder specific keys

- Both saved & unsaved
- which supports intellisense in the files

- Always show workspace name
- Section root should be folder in case of single folder workspace