Some code quality

[nicopap]

• Use QueryItem<Self::Query> instead of <Self::Query as WorldQuery>::Item<'_> (I think I might have missed some instances
• use PartialEq derive over manual impl
• use a reduce over a fairly complex loop setup in batch_and_prepare_render_phase
• Move the construction of BatchMeta from batch_and_prepare_render_phase to BatchMeta::new
• Make the BatchMeta fields private.
• Call render_range in render instead of copy/pasting the code.
• Replace the odd handling of arrays in SetMesh2dBindGroup::render

[nicopap]

Previous discussion in #35. Closed due to some GH bug