Do not wrap operators onto a new line in Kotlin sources

[vlsi]

What's changed

OperatorWrap now only reformats Java compilation units, leaving Kotlin (and other non-Java JavaSourceFiles) untouched. Adds a Kotlin test.

Why

In Kotlin a newline terminates an expression, so a leading binary operator is parsed as a unary operator on a new statement. With the default WrapOption.NL style the recipe moves a binary operator to the start of the next line:

val s = "aaa" + "b" +
    "c"

becomes

val s = "aaa" + "b"
    + "c"

The trailing + "c" is now a unaryPlus on a separate statement, so the code no longer compiles. This surfaced running a CodeCleanup composite over Apache JMeter's mixed Java/Kotlin sources — a letsPlot(...) + geomLine {...} + ... chain was broken the same way.

The recipe's visitBinary moves operators purely by relocating whitespace, which is only valid under Java's newline rules. Restricting the visitor to J.CompilationUnit (rather than every JavaSourceFile) keeps the Java behaviour and stops it corrupting Kotlin.

How to verify

./gradlew test --tests "*.OperatorWrapKotlinTest" --tests "*.OperatorWrapTest" — the new Kotlin test passes and the existing Java suite (19 tests) is unchanged.