bugs in foundry test generation

Here, I collect bugs in foundry test generation

### contract name

```
Error (2333): Identifier already declared.
--> test/Test.1904265591758374514.sol:6:1:
|
6 | contract Test is Test {
```

should be for example `Test1 is Test`

### fallback

call to fallback function is written as an empty string

```
Error (2314): Expected identifier but got '('
--> test/Test.8771174626403390381.sol:19:16:
|
19 | Target.();
```

### null byte

files contains \\0 (written as below)
```
Error (8936): Expected even number of hex-nibbles.
--> test/Test.2952294588457979761.sol:23:29:
|
23 | Target.renounceRole(hex"", address(0xa329c0648769a73afac7f9381e08fb43dbea72));
|
```