Adding support for v12 and some additional improvements

[macagr]

This commit adds support for Foundry VTT v12 to the Waterdeep-City-of-Splendors Module.

Changes:

• Executing the script after packs have been added. This allow the execution to use the folders and everything by the packs.
• Adding 2 functions to allow managing the folders via code: getFoldersIdsByNames and getIdByName. The idea is to manage everything by changing the variable folderNames if required.
• Modified the addData function to deal with duplicated data and adding entry pages to the existing journal entries.
• Modifying the verified version of Foundry as I tested it on my local instance.

[webmaster94]

I updated the waterdeep.js file to include your changes. I did not merge this branch because I needed to make a bunch of changes on my end anyway. Thank you for the help. I credited you in the release.