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### What it does
Checks for use of `.collect::<Vec<String>>().join("")` on iterators.
### Why is this bad?
`.collect::<String>()` is more concise and might be more performant
### Example
```
let vector = vec!["hello", "world"];
let output = vector.iter().map(|item| item.to_uppercase()).collect::<Vec<String>>().join("");
println!("{}", output);
```
The correct use would be:
```
let vector = vec!["hello", "world"];
let output = vector.iter().map(|item| item.to_uppercase()).collect::<String>();
println!("{}", output);
```
### Known problems
While `.collect::<String>()` is sometimes more performant, there are cases where
using `.collect::<String>()` over `.collect::<Vec<String>>().join("")`
will prevent loop unrolling and will result in a negative performance impact.
Additionally, differences have been observed between aarch64 and x86_64 assembly output,
with aarch64 tending to producing faster assembly in more cases when using `.collect::<String>()`
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