Support "string array" in settings UI

[alefragnani]

The settings baseFolders and ignoredFolders should be updated to allow to be defined in Settings UI, not only JSON

This:

    "projectManager.git.baseFolders": {
      "type": "array",
      "default": [],
      "description": "%projectManager.configuration.git.baseFolders.description%"
    },

Should become this:

    "projectManager.git.baseFolders": {
      "type": "array",
      "default": [],
      "items": {
        "type": "string"						
      },
      "description": "%projectManager.configuration.git.baseFolders.description%"
    },