Suggest `Option<&T>` instead of `&Option<T>`
closes#13054
```rust
// bad code
fn foo(a: &Option<T>) {}
fn bar(&self) -> &Option<T> {}
// Use instead
fn foo(a: Option<&T>) {}
fn bar(&self) -> Option<&T> {}
```
Handles argument types and return types in functions, methods, and closures with explicit types. Honors `avoid_breaking_exported_api` parameter.
See this great [YouTube video](https://www.youtube.com/watch?v=6c7pZYP_iIE) with the in-depth explanation.
### Open Questions
These are not blocking, and could be done in separate PRs if needed.
* [ ] Should `&Option<Box<T>>` be suggested as `Option<&T>` -- without the box? Handled by [clippy::borrowed_box](https://rust-lang.github.io/rust-clippy/master/index.html#/borrowed_box)
* [ ] Should `&Option<String>` be suggested as `Option<&str>` -- using de-refed type?
### Possible Future Improvements
These cases might also be good to handle, probably in a separate PR.
```rust
fn lambdas() {
let x = |a: &Option<String>| {};
let x = |a: &Option<String>| -> &Option<String> { todo!() };
}
fn mut_ref_to_ref(a: &mut &Option<u8>) {}
```
changelog: [`ref_option`]: Suggest `Option<&T>` instead of `&Option<T>`
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