Add RenderGuiLayerEvent.Pre#isGoingToRender(), allowing to determine whenever layer is actually going to render on screen

[DBotThePony]

Additionally, adds new RegisterGuiLayersEvent API methods, allowing to specify own "rendering condition" which is visible to other mods in isGoingToRender()

Introduces no breaking changes, everything that is declared as public API is binary compatible.

From #neoforge-github:

what's the usecase of having this isGoingToRender parameter?

Not duplicating logic regarding whenever hud element is actually rendered
Currently, all hud elements are firing this event
Even if they render nothing
E.g. Hunger layer event is still fired if player is in creative, so mod makers have to duplicate vanilla logic in their event listener to check separately if they actually need to draw their hunger bar replacement or similar
This check differ a little from version to version, which also creates error prone situations during mod porting
And as well it all being not very intuitive at first that layer events are called even if player have pressed F1

This PR creates middle ground, events continue to get called, so mods depending on this behavior don't get broken, while also addressing issue regarding checking if layer has actually rendered anything without duplicating logic
I have no idea why this havent been merged yet

[CLAassistant]

All committers have signed the CLA.

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

[neoforged-compatibility-checks]

@DBotThePony, this PR introduces breaking changes.
Fortunately, this project is currently accepting breaking changes, but if they are not intentional, please revert them.
Last checked commit: 5810b19b239990c18f982b7ea97a3cd074bd6533.

neoforge (:neoforge)

• net/neoforged/neoforge/client/event/RenderGuiLayerEvent$Pre
  • <init>(Lnet/minecraft/client/gui/GuiGraphics;Lnet/minecraft/client/DeltaTracker;Lnet/minecraft/resources/ResourceLocation;Lnet/minecraft/client/gui/LayeredDraw$Layer;)V: ⚠ Method was lowered in visibility
• net/neoforged/neoforge/client/event/RenderGuiLayerEvent$Post
  • <init>(Lnet/minecraft/client/gui/GuiGraphics;Lnet/minecraft/client/DeltaTracker;Lnet/minecraft/resources/ResourceLocation;Lnet/minecraft/client/gui/LayeredDraw$Layer;)V: ⚠ Method was lowered in visibility
• net/neoforged/neoforge/client/gui/GuiLayerManager$NamedLayer
  • <init>(Lnet/minecraft/resources/ResourceLocation;Lnet/minecraft/client/gui/LayeredDraw$Layer;)V: ❗ API method was removed