`-5` as `global` when used with struct accessing

[tinkerer-red]

Many functions which accept structs will allow for -5 to represent global this is obviously an out of date method to do this, and we should leverage our type safety tool to allow for avoiding this.

this is also true for our internal struct accessor functions __GMLCexecuteGetPropertySelf and __GMLCexecuteSetPropertySelf as well as method overrides.

This is a feature which is planned for the same update as our function database addition.