### What it does
Checks for `FileType::is_file()`.

### Why is this bad?
When people testing a file type with `FileType::is_file`
they are testing whether a path is something they can get bytes from. But
`is_file` doesn't cover special file types in unix-like systems, and doesn't cover
symlink in windows. Using `!FileType::is_dir()` is a better way to that intention.

### Example
```
let metadata = std::fs::metadata("foo.txt")?;
let filetype = metadata.file_type();

if filetype.is_file() {
    // read file
}
```

should be written as:

```
let metadata = std::fs::metadata("foo.txt")?;
let filetype = metadata.file_type();

if !filetype.is_dir() {
    // read file
}
```