New lint: trait item removed

[whentze]

Going from

pub trait Foo {
  fn foo();
}

to

pub trait Foo {
}

is a breaking change. There should be a lint for that.

[obi1kenobi]

Agreed, thanks for opening this! If you're interested in adding this lint, I'd be happy to mentor and I think it should be fairly straightforward to do.

It depends on obi1kenobi/trustfall-rustdoc-adapter#85 which is also fairly straightforward, completely analogous to existing code.