Test: add java source files as JavaSourceRoot

so that those can be properly populated in SingleJavaRootsIndex

compiler/fir/analysis-tests/testData/resolve/problems/multipleJavaClassesInOneFile.fir.txt

@@ -3,5 +3,5 @@ FILE: main.kt
 
     public final fun test(): R|kotlin/Unit| {
         lval some: R|foo/Some| = R|foo/Some.Some|()
-        lval another: <ERROR TYPE REF: Unresolved name: Another> = <Unresolved name: Another>#()
+        lval another: R|foo/Another| = R|foo/Another.Another|()
     }

compiler/fir/analysis-tests/testData/resolve/problems/multipleJavaClassesInOneFile.kt

@@ -11,5 +11,5 @@ package foo
 
 fun test() {
     val some = Some()
-    val another = <!UNRESOLVED_REFERENCE!>Another<!>()
+    val another = Another()
 }