Feature Request: Multi Select QuickPick list

[a-secret-me]

It would be really nice to have an option to select multiple items from a quick pick list then have them all returned as a concatenated string. Would require two variables one that's something like multiSelect that you can set to true. This would be use to set the "canSelectMany" option to true. https://github.com/augustocdias/vscode-shell-command/blob/master/src/lib/CommandHandler.ts#L137 A second option would be something like multiSelectSeperator which has a default value (" " seems obvious to me) and can be used to set what you'd like to be concatenated between the selected output values.