Implement outlineViewType setting that changes the Project Outline View (#3799)

[ar1m4n]

This change addresses item #[3799]

This changes visible behavior, documentation and configuration]

The following changes are proposed:

• New config option "cmake.outlineViewType" that accepts one of 2 values - list or tree
• If "cmake.outlineViewType" is set to "list", the Project Outline View will show all cmake targets in a "flat" view
• If "cmake.outlineViewType" is set to "tree", the Project Outline View will show all cmake targets in a hierarchical view

The purpose of this change is to enable users to choose witch type of view to use. In my case, I find the "tree" view much more useful

Changes:

• A ConfigurationReader argument is added to ProjectNode`s constructor
• ProjectNodes::update uses the "cmake.outlineViewType" to produce a different output
• An on change event handler is added to refresh the Outline View each time the value of the new config option is changed

[ar1m4n]

@microsoft-github-policy-service agree