Derive macro for input doesn't support any output type

We'd like to support the following code:
```rs
#[derive(Clone, Input)]
#[inc_complete(id = 20, output = Arc, storage = MyStorage)]
pub struct GetCrateGraph;
```
But we get an error because we seem to be parsing an expression instead of a type:
```rs
error: comparison operators cannot be chained
--> src/incremental.rs:128:48
|
128 | #[inc_complete(id = 20, output = Arc, storage = DbStorage)]
| ^
```
We should support any type in this position.