Improve boilerplate for Trait impl

Currently impl for a struct and traits look like this:

struct Services {};

impl Services {

}

impl Clone for Services {
    fn clone(&self) -> Services {
        Services {}
    }
}

Now if we add lifetimes, and/or generics, the syntax gets out of hand rather quickly.

struct Services<'a, T> { wrap_drive: &'a WarpDrive<T> };

impl<'a, T> Services<'a, T> {

}

impl<'a, T> Clone for Services<'a, T> {
    fn clone(&self) -> Services<'a, T> {
        Services {
          // ..
         }
    }
}

What I'm proposing is to be able to write this instead:

struct Services<'a, T> { wrap_drive: &'a WarpDrive<T> };

impl<'a, T> Services<'a, T> {
    fn beam_all_services() { }
    
    // ..snip..snip
    
    impl Clone for Self {
        fn clone(&self) -> Services<'a, T> {
            Services { 
               // ... 
            }
        }
    }
}

Advantages:

• Reduce boiler plate for impl when it's an in-module struct.
• Encourage in-module blocks to be cleanly encapsulated into the parent impl block, allowing for easier source comprehension and maintenance.
• While the above is a trivial case, code bases like actix and Hyper which makes heavy use of generics can be made much more readable removing redundant type information from each impl blocks.
• This is all entirely optional. So, no breaking changes.

Disadvantages:

• impls are no longer just confined to the top-level, but also be one level nested.
• Compiler complexity.

Start with the proposed nested impl examples in this issue and review the surrounding discussion for unresolved design questions. No implementation files or tests are named; determine the Rust syntax and compiler areas affected before pursuing it. Done would require an accepted design and corresponding compiler and test changes.