Fix issues with JSDoc generation on goog_module

[moniika]

Running script for JSDoc generation on goog_module reveal some issues with the generated files:

• Missing content
• Pages missing fully qualified namespace (Abstract instead of Blockly.Events.Abstract)
• Fatal error when staging to devsite (caused by empty header with empty string id)
• Duplicated enum description (pre-existing, non-urgent issue)

This may be a matter of a bug with the process or library used to generate jsdoc or it could be an issue with the code in core.

[moniika]

Still seeing issues with devsite, but missing content seems to be resolved.

[moniika]

Current status of jsdoc generation:

• Pages are generating with fully qualified namespace (due to addition to @namespace and @alias)
• No more fatal error staging after fixing @package annotation
• Most of missing content issues have been resolved by the addition of @alias to properties
• JSDoc for constructors is generating after adding @class annotation

Remaining issues:

• JSDoc for private methods/properties is generated when it shouldn't
  • fix: add @private annotations
  • temporary fix: manually edit generated jsdoc
• Missing some generated JSDoc content on pages
  • JSDoc for inherited properties missing
  • links, such as to parameter types, are missing
• Investigate modules that have been re-exported under different namespaces (ex: Blockly.blocks.Blocks and Blockly.Blocks) and decide whether we should have jsdoc generated for both