Add special cases for move from `Rc`/`Arc` errors.

Add special cases for move from `Rc`/`Arc` errors.

This commit special cases the move out of borrowed content error,
previously:

```
error[E0507]: cannot move out of borrowed content
 --> src/main.rs:7:10
  |
7 |     drop(x.field);
  |          ^ cannot move out of borrowed content
```

to instead mention that it is a move out of a `Rc`/`Arc` which is more
helpful:

```
error[E0507]: cannot move out of an `Rc`
 --> src/main.rs:7:10
  |
7 |     drop(x.field);
  |          ^ cannot move out of an `Rc`
```