Fix for untradeable but alchemizable items according to issue #1249

What have you done in this MR?

• I've added an entry to the ItemConfigParser so that the node will be read from the item_config.json;
• Added an entry to the ItemDefinitino so that it's possible to check whether an item can be alchemized;
• I've altered the condition within the ModernListeners so that it will check whether an item is marked as alchemizable in the item_config.json;
• Changes done to the item_configs.json, certain items that are untradeable now have the "alchemizable" key - value pair there.

Are there any tricky things testers should keep an eye out for?

• No

• [] Yes, as follows:

• I have tested these changes thoroughly.

• item alchemizable but not tradeable - works (3748, 3757 ,3758)
• item tradeable but not alchemizable - works (3759)
• item not tradeable and not alchemizable - works (4558)
• item tradeable and alchemizable - works (3747)

closes #1249 (closed)

• This requires extra testing due to changes to architecture or other similarly risky changes.

• I used the Thanos Tool for any JSON edits where possible, and have attached screenshots of any changes.

• Was not yet aware of this tool. I'll have a look into it when i run into (another) JSON change.

• I acknowledge that this contribution will be released under the AGPL license.

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