overhaul: Explorer Mode structure changes :: infrastructure setup

[mileswest07]

• Removed unused placeholder icons
• Expanded space of placeholder spritesheet to make room for more variants, likely needed and will be expanded later
• Refactored rawData to no longer reference old placeholders
• Refactored some data in rawData for area names using unofficial sources
• Refactored CSS definitions to be simplified, making Explorer Mode image extraction easier
• Fixed offset issue with MZM Unified sprites on spritesheet
• Added new icons to MZM Unified spritesheet: Item Orb, Randomizer
• Fixed bug: if UseSprites is unset but UseMZMSprites is set, then MZM Unified sprites will still show. Code now checks both flags before deciding to show MZM Unified sprites or not.
• Fixed bug: selecting Z1M1 option was selecting the wrong games. This has been fixed.
• Fixed bug: when selecting AM2R for Randomizer Mode, the Extreme Labs hint icon was not loading properly. This has been fixed.
• Fixed bug: when selecting AoL for Randomizer Mode, the Dash Boots hint icon was not loading properly. This has been rectified.
• Refactored map rawData into mapTree structure: instead of listing all of the nodes as a flat array of hubs, all nodes are set up in a tree structure of parents, children, and vines tied via hubId-vineToHubId keys. Explorer code will be updated in a future PR; will not work if Explorer.html is reenabled.
• Refactored rawData input to read from multiple JSON files instead of a .JS file import. This reduces load on system as it will only load required files and data struct. From this point on, code changes will need to require data and struct testing on each affected JSON file.
• Added multiple JSON files to data/*.json