[Finishes #72141728] Support non-unique (Blockly) level names in custom scripts

defines a special syntax for including Blockly app levels in custom Dashboard scripts using a specially-formatted colon-separated name 'blockly:Studio:100', where the first string is "blockly", the next string is the level's Game name, and the last string is the level_num defined in the appropriate game's 'levels' module.
@cpirich please review