No longer use java.applet as it's scheduled for removal.

[modmuss50]

Seems to work, and wasnt too crazy, this should help ensure future java version support, see: https://openjdk.org/jeps/8345525

Tested only in b1.8.1 so far, needs testing in a wide range of versions.

Can we take this opertunity to fix some of the bugs with the applet versions, especially the incorrectly sized windows?

[Player3324]

Fine imo, but don't merge before we at least verified it works with a JDK build that has applets removed - unless it substantially improves using these old versions for other reasons.

[modmuss50]

It doesn't improve much, I made the PR mostly so it's not forgotten about.

[modmuss50]

This has been proposed to be removed in J26: https://openjdk.org/projects/jdk/26/

Once there is an EA build for 26 this should be re tested.

[modmuss50]

Tested with the latest Java 26 EA build 17 this works fine for most older versions, but 1.4.7 is proving to be a bit tricky as it uses the applet classes in its own obfucated classes that the same gamepatch doesnt cover.

I think the solution here is to make a builtin transform that runs on every single class load, to point to the stubbed classes. This has an additional benefit of also patching mods that use applet classes (do any exist?).

I may also look into only applying these changes when running with Java 26 or later as there is no point in breaking something that already works.