fix: Make sure item tooltips are cached properly

[kristofbolyai]

Fixes #3079.

This PR doesn't fix a single issue, rather, it fixes two of them:

1. The general logic behind TooltipUtils caching was there, but it did not use Objects.equals :(. This unfortunately made it so the tooltips were never pulled from the cache.
2. FakeItemStack (aka, chat items, and more) had special tooltip building logic, basically they once built a fake tooltip, then it was parsed and rebuilt by ItemStatInfoFeature with slightly different tooltip options. This made the cache to be invalidated every render, and made it so item tooltips were calculated more than one times per render for these items. Now, FakeItemStack generates it's tooltips in a standard way (as every other feature does), making it actually use the cache. Fixing multiple generations per render makes no sense now, as it's mostly part of the design of the system, and with caching present, this virtually presents no overhead.