Fix Scala parser gaps surfaced by prethink integration testing

ScalaTreeVisitor: mirror the else branch's expression-wrapping fallback
that the then branch already had, so `if (x) a else b` with expression
operands parses (closes asymmetry that threw UnsupportedOperationException).
Add `case j: J => new S.StatementExpression(Tree.randomId(), j)` fallbacks
at ~25 visitUnknown sites where the parser previously crashed on any J
that wasn't exactly an Expression/Statement — covering visitWhileDo
body/cond, visitForDo body/iterable, visitReturn, visitThrow,
visitMatchImpl selector, visitAssign lhs/rhs, visitInfixOp /
visitBinaryOperation / visitInfixMethodCall operands, visitPrefixOp /
visitPostfixOp operand, visitParentheses inner, visitTyped,
visitTypeApply asInstanceOf/isInstanceOf, visitAppliedTypeTree args,
method call target, ArrayAccess array/index, NewArray /
NewArrayWithType elements, NewClassWithArgs constructor args,
annotation args, tuple elements. Try body/finalizer now also accept
Statement, matching the existing ParsedTry behavior.

ScalaParser.sourcePathFromSourceText: was hard-coded to "file.scala"
so every source in a multi-file test collided on the same path and
clobbered each other on print round-trip. Extract package + class
name via a shared derivedRelativePath helper (reusing logic from
parse()) so each source gets a distinct path.

7 new regression tests covering if-else-as-expression (literal/ident
operands), return/throw/assign with if-rhs, binary/tuple/paren with
if-operand, while-with-unit-body, and multi-file distinct paths. Full
rewrite-scala suite passes.

Author: jkschneider

rewrite-scala/src/main/java/org/openrewrite/scala/ScalaParser.java

@@ -32,7 +32,6 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.*;
-import java.util.function.Function;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -46,26 +45,25 @@ public class ScalaParser implements Parser {
     private final boolean logCompilationWarningsAndErrors;
     private final JavaTypeCache typeCache;
 
-    @Override
-    public Stream<SourceFile> parse(@Language("scala") String... sources) {
-        Pattern packagePattern = Pattern.compile("\\bpackage\\s+([.\\w]+)");
-        Pattern classPattern = Pattern.compile("(class|object|trait|case\\s+class)\\s*(<[^>]*>)?\\s+(\\w+)");
+    private static final Pattern PACKAGE_PATTERN = Pattern.compile("\\bpackage\\s+([.\\w]+)");
+    private static final Pattern CLASS_PATTERN = Pattern.compile("(class|object|trait|case\\s+class)\\s*(<[^>]*>)?\\s+(\\w+)");
+
+    private static String derivedRelativePath(String sourceCode) {
+        Matcher packageMatcher = PACKAGE_PATTERN.matcher(sourceCode);
+        String pkg = packageMatcher.find() ? packageMatcher.group(1).replace('.', '/') + "/" : "";
 
-        Function<String, String> simpleName = sourceStr -> {
-            Matcher classMatcher = classPattern.matcher(sourceStr);
-            return classMatcher.find() ? classMatcher.group(3) : null;
-        };
+        Matcher classMatcher = CLASS_PATTERN.matcher(sourceCode);
+        String simpleName = classMatcher.find() ? classMatcher.group(3) : Long.toString(System.nanoTime());
+
+        return pkg + simpleName + ".scala";
+    }
 
+    @Override
+    public Stream<SourceFile> parse(@Language("scala") String... sources) {
         return parseInputs(
                 Arrays.stream(sources)
                         .map(sourceFile -> {
-                            Matcher packageMatcher = packagePattern.matcher(sourceFile);
-                            String pkg = packageMatcher.find() ? packageMatcher.group(1).replace('.', '/') + "/" : "";
-
-                            String className = Optional.ofNullable(simpleName.apply(sourceFile))
-                                                       .orElse(Long.toString(System.nanoTime())) + ".scala";
-
-                            Path path = Paths.get(pkg + className);
+                            Path path = Paths.get(derivedRelativePath(sourceFile));
                             return Input.fromString(path, sourceFile);
                         })
                         .collect(Collectors.toList()),
@@ -154,7 +152,7 @@ public ScalaParser reset() {
 
     @Override
     public Path sourcePathFromSourceText(Path prefix, String sourceCode) {
-        return prefix.resolve("file.scala");
+        return prefix.resolve(derivedRelativePath(sourceCode));
     }
 
     public static ScalaParser.Builder builder() {