Construct type_name from ComponentId

[alice-i-cecile]

What problem does this solve or what need does it fill?

When attempting to debug and display error messages for ComponentId-related code, we can only report the raw ComponentId(usize) to the users. This is not very helpful for debugging purposes.

What solution would you like?

1. When components are initialized via init_component::<T>, store the type name in Components.
2. Provide a Components::type_name(component_id: ComponentId) -> Option<String> method.
3. Allow users to store a custom string when initializing a component manually, to allow users to provide user-friendly types for non-Rust components.

What alternative(s) have you considered?

a) Store the type name as part of ComponentId. This would be extremely convenient, but increases the size of a struct in the hot path of the ECS.
b) Provide a method to get an Option<TypeId> from a ComponentId, then convert that into a type name. Unfortunately, Rust does not provide any tools for the second part of this step: type names can only be constructed from values and types.

Additional context

#1481 needs this to significantly improve error reporting.

[alice-i-cecile]

This is already accessible: see the name field on Components -> ComponentInfo -> ComponentDescriptor.