Support more constant types

[Daomephsta]

Adds support for short, byte, and char simple constants; plus byte and short flag constants.
Boolean simple constant support is not included, as parameter names are adequate for giving true & false meaning.
Character flag constant support is not included, as chars aren't really meant to be used as integers, and only differ from shorts in that they are unsigned. I'm considering it though, Mojang does plenty of weird stuff.

Supersedes #5.

[OroArmor]

Not sure that byte constants are working. Just tested this or with the entity status constants, and it did not work. The other unpicks work, though it could be the unpicks from that that are wrong

[Daomephsta]

@OroArmor
Try again with the latest commits please. I've verified the tests are generating and transforming bytecode as expected. If it's still not working, there might be a bug in the parser.

[liach]

❤️

[OroArmor]

Can confirm that this is working with byte constants

[Daomephsta]

I've looked into char flags and decided against them. They're more difficult to implement due to Character not extending Number, a class the flag code depends on a fair bit. It may be possible to remove that dependency, or create an UnsignedShort class to use in place of Character; but I didn't find any char flags in 21w14a, so I vote we deal with that edgecase only if it ever occurs.

[liach]

Yeah, we probably won't use char as integertype. but we should still use them as literal types as they do exist in places like string concatenation, indexOf, etc.

[Daomephsta]

Yeah, we probably won't use char as integertype. but we should still use them as literal types as they do exist in places like string concatenation, indexOf, etc.

char simple constant support has been in this PR since the beginning