A bit better diagnostic on EntityAccessDenied.

[HughHoyland]

Description

Motivation and Context

Currently, all calls to get_component_storage() are just unwrap()ed.

This is clearly a temporary code that, unfortunately, is staying with us.

With this change, at least, the user gets a list of types that the calling System needed access to. Currently, it's anybody's guess, and in a deep call trees, it's difficult to see.

How Has This Been Tested?

I removed access to a necessary Component in one of my Systems, and instead of generic unwrap() panic, got a message:

EntityAccessDenied for view: (&macroquad_tiled_redux::map_point::MapPoint, &stepsonsrl::mob::Mob, core::option::Option<&stepsonsrl::mob::interaction::Interactable>, &stepsons_buffdebuff::ecs::components::HitPoints, legion::internals::entity::Entity): AccessDenied

Now I know which Components to add to my System.

Checklist:

• Acknowledged that by making this pull request I release this code under an MIT/Apache 2.0 dual licensing scheme.
• My code follows the code style of this project.
• n/a If my change required a change to the documentation I have updated the documentation accordingly.
• n/a I have updated the content of the book if this PR would make the book outdated.
• n/a I have added tests to cover my changes.
• n/a My code is used in an example.