Anvil CUIItemUpgrade implemented

[Mervandeli]

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

What is the current behaviour?

-Item Upgrade not implemented

What is the new behaviour?

-The CUIItemUpgrade class has been implemented, and the UI behaviors work the same as in the original 1298 Client. Items can be upgraded correctly.

Why and how did I change this?

-The items in the ItemUpgrade window are copied from the inventory and backed up. When the window is closed or the Cancel button is pressed, the items are restored from the backup. A backup is used to prevent errors when switching between Inventory and ItemUpgrade. If the upgrade process succeeds or fails, the backup is updated accordingly.

Checklist

• I have performed a self-review of my own code.
• Where applicable, I have checked to make sure that this doesn't introduce incompatible behaviour with the official 1.298 server (e.g. unofficial opcodes or behavioural differences).
• I have checked to make sure that this change does not already exist in the codebase in some fashion (e.g. UI already implemented under a different name).

[Mervandeli]

Scroll check and other reviews solved.

[twostars]

Okay. I cleaned things up a little bit to just reduce the number of things to bother commenting on, fixing a few bugs in the process.

Beyond what I've reviewed in particular, I just want you to pay special attention to the items and their management in general. Originally they were leaking quite a bit; now they appear to be leaking a little, but I haven't really done too thorough a check over that. I suggest paying special attention to it yourself before I do a final pass over it (after you've addressed my related review comments for it).

Finally, I'm still a bit hesitant on the Trina thing. I would very much like if you could explore this behaviour without having to check item IDs; it is definitely possible to not have to hardcode item IDs (or names for that matter) here.

It might help to just not think about it as it being just Trinas vs Scrolls.