Update InventoryID to non-integer strings and add soft delete

[varunghat]

Update InventoryID from ordered integers to hex strings to remove linearity

• Ensure all are non-integer so they throw a warning instead of silently accepting an integer ID during access
• Soft delete languages that get removed, so that InventoryIDs stay consistent between releases
• Add mapping file from old ID to new ID and entry in Readme
• Add a test to ensure IDs are consistent with changes
• Website links need to redirect from old view/InventoryID pages to new view/InventoryID pages, with an empty page for deleted languages (Might need to open this issue separately on the cldf side?)