Add more functionality static expressions

[GearsDatapacks]

We want to be able to reference storages and scoreboard from static expressions, as well as probably compile-time-known expressions like 1 + 1. I propose we allow any expression which is allowed in a compile-time variable, after #13 is resolved, and the additional referencing of macro variables, and resources, assets and functions.
So that the syntax for referencing storages doesn't conflict with the syntax for referencing resources, we should make the latter require the res keyword, like fn does