Ensure kit selection quickPick doesn't show on non CMake projects

[andreeis]

Fix for #1578.
Plus the following:

• rename for commands related to edit cache UI, they were confusingly named openConfiguration
• edit cache was not guarded by full feature set, being available in the UI for non CMake projects
• resetState command is useful even if the current project is seen as non CMake (mostly to identify bugs when the extension analyzes wrong this aspect). It's inconvenient to have resetState not available (it's hard to get out of a bad state when investigating some bugs)
• the extension would show full features (until the next reload) even if the single project in the workspace would be disabled, because we were calculating the state of the workspace too early