feat: add SpoonCheckstyleCompliantPrettyPrinter to be compliant with Spoon's own formatting rules

We want to use Spoon to transform the code of Spoon. For this, we need a Spoon pretty-printer that is compliant with Spoon's checkstyle.

The idea is to create a class `SpoonCheckstyleCompliantPrettyPrinter` which extends `DefaultJavaPrettyPrinter`

Here are the rules with the number of violations in `src/main/java` today:

```
2 [modifierorder]
2 [rightcurly]
2 [unusedimports]
5 [regexpsinglelinejava]
77 [whitespaceafter]
99 [nowhitespacebefore]
167 [parenpad]
237 [regexpsingleline]
1629 [whitespacearound]
```