Add shortenFullyQualifiedTypes step (fixes #2945)

[maxandersen]

headsup - I used llm to generate this; first time contributing to this area but did a quick read and seemed to match similar operations and been using it in my own workflows so it at least works for my usecases :)

Summary

Adds a new Java formatter step that replaces fully qualified type names with simple names and adds the required imports. Designed to clean up LLM-generated code and other sources that use inline FQNs unnecessarily.

Before

public class UserService {
    private final java.util.Map<String, java.util.List<String>> cache = new java.util.HashMap<>();
    public java.util.List<String> getUsers(java.util.function.Predicate<String> filter) throws java.io.IOException {
        java.util.List<String> result = new java.util.ArrayList<>();
        return result;
    }
}

After

import java.io.IOException;
import java.util.*;
import java.util.function.Predicate;

public class UserService {
    private final Map<String, List<String>> cache = new HashMap<>();
    public List<String> getUsers(Predicate<String> filter) throws IOException {
        List<String> result = new ArrayList<>();
        return result;
    }
}

Implementation

• Uses JavaParser for AST-based type identification (no regex false positives from strings, comments, or non-type contexts)
• Position-based text replacement preserves original formatting exactly
• Configured with BLEEDING_EDGE language level to support Java 14–25 syntax
• Deduplicates AST visits (JavaParser visits instanceof pattern nodes twice)

Safety

Skips rewriting when:

• Two different FQNs map to the same simple name (conflict)
• An existing import already claims the simple name for a different type
• The file can't be parsed (returns input unchanged)
• java.lang.* types (shortened without import)
• Same-package types (shortened without import)

Usage

Gradle:

spotless {
    java {
        shortenFullyQualifiedTypes()
        importOrder()
        removeUnusedImports()
    }
}

Maven:

<java>
    <shortenFullyQualifiedTypes/>
    <importOrder/>
    <removeUnusedImports/>
</java>

Tests

16 tests covering: basic shortening, conflict detection, existing import conflicts, java.lang handling, same-package handling, idempotency, and Java 14–25 syntax (instanceof patterns, switch patterns, records, sealed classes, text blocks, var+generics, lambda casts).

Fixes #2945