[breaking] Introduce bench suite + query/system performance improvements + other

[Indra-db]

changes:

• benchmark suite that measures performance of several ecs functions. This will be tracked release over release to prevent regressions and test for optimizations.
• introduction of field and field_mut instead of just field [breaking❗]
• introduction of get_field and field instead of just field. get returns option as before, the non-get variant panics instead. [breaking❗]
• TableIter::iter() (for i in it.iter()) now returns a FieldIndex type instead of usize. This allows for mitigating bound checking. [breaking❗]
• Fields don't deref to the slice components anymore, Index traits are implemented instead.
• introduction of .len(), .get(), .get_mut() on Field and FieldMut types
• query/observer/system now share the same internal iteration code, making maintenance and bug fixing easier.
• query/observer/system iteration speed is drastically improved, ranging from 80-96% improvements in most query benchmarks.
• .each_iter() on query-like types is removed, use .run() instead. [breaking❗]