Test ProcMacros

[kyleoneill]

AST tests would be shorter and easier to read if there were a proc macro to run them. AST tests are extremely simple, a code string is evaluated into an AST and then the pieces of it are checked to be equal to the input pieces. Proc macros work well with tokens and ASTs, so this should not be too bad to write.

An example of what this could look like is:

#[chimera_test]
fn test() {
    ASSERT EQUALS 1 1;
}