Move common method for a CapsuleManager to trait, this would reduce the ...

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | None
| License       | MIT
| Doc PR        | None

* Move common method for a CapsuleManager to trait, this would reduce the requirement to produce new CapsuleManager for other component in the future (e.g: laravel/framework#5032)
* Also remove duplicate "require-dev" component (when already explicitly declare in "require").

Why have you removed the support dependency? It will be loaded anyway, because the other dependencies require it. Should we not keep the dependency for convention?