entirely rewrote memory usage feature (base traits)

- `MemoryUsage` - everything that can report memory usage (Vec, String, &str, u64, etc)
- `MemoryUsageStatic` - everything that can report memory usage in a const context, with `self` in a fn (&'static str (ie. string literals), u64)
- `MemoryUsageConst` - everything that can report memory usage in a const context, without a value (ie. `self`) (u64 etc)
- impl `MemoryUsage` for reference types where `T: MemoryUsage`
- impl all 3 traits for primitives (except str) and arrays