Inserting Resource Tuples

[Wuketuke]

Objective

Some structs like Systems or Plugins can be inserted via tuple, but not Resources, which greatly annoyed me. Fixed #16398

Solution

I very closely copied what plugins do in bevy_app. I also modified every function signature relating to inserting Resources. However, I still have some open questions about my implementation:

• I dont exaclty know what #[track_caller] does. I tried faithfully keeping that functionality, but its possible that I broke something.
• Somehow, World::insert_resource_with_caller is now unused, and I dont what went wrong
• Some other functions like App::init_resource, which dont currently support tuples. Should I also rework these functions?
• should i rename insert_resource to insert_resource to reflect this new feature?
• I removed the generic function signature in a file on line 118 and 131, which hopefully didnt break anything

Testing

I added an example in the documentation, and two new unit tests

[alice-i-cecile]

We've chatted about this before, and the SME-ECS (and Cart) aren't fully sold that this is worth the added compile time. To move forward here, you'll need to measure the impact.