Remove wildcard * type variables

[smores56]

It seems that the * type variable is more trouble than it's worth, and the confusion it causes to beginners and experienced Roc devs alike is cause for removal.

• We'll need to replace all usages of * with vars in the *.roc builtins
• We should continue to parse them, but add a deprecation warning
• We can remove them from the rest of the compiler