Handle Kotlin sources in MockitoWhenOnStaticToMockStatic

[MBoegers]

Summary

• Fix ClassCastException when MockitoWhenOnStaticToMockStatic runs on Kotlin sources containing Mockito.when(StaticClass.staticMethod(...)) (reported by Sunbit; blocks UpgradeSpringBoot_4_0).
• Dispatch on compilation-unit type: existing Java logic is unchanged; a new Kotlin visitor recognizes mockStatic(X::class.java).use { ... } as the wrapping scope and rewrites the inner Mockito.when(X.static()) to call when on the lambda parameter (handles both implicit it and named parameter):

// before
mockStatic(X::class.java).use {
    `when`(X.static()).thenReturn(value)
}
// after
mockStatic(X::class.java).use {
    it.`when`<R> { X.static() }.thenReturn(value)
}

• Also reuses an existing class-level MockedStatic<X> property (e.g. lateinit var set in @BeforeEach) when present.

Out of scope (deliberately): the fresh-wrap case for Kotlin (no enclosing .use and no class-level MockedStatic property). The recipe now degrades to a no-op for that case instead of crashing; the structural Kotlin equivalent of the Java tryWithMockedStatic path will be a follow-up.

Resolves moderneinc/customer-requests#2400.

Test plan

• ./gradlew test --tests "*MockitoWhenOnStaticToMockStaticTest*" passes, including the five new Kotlin tests:
  • shouldRewriteKotlinMockitoWhenInsideMockStaticUseWithImplicitIt (Sunbit reproducer)
  • shouldRewriteKotlinMockitoWhenInsideMockStaticUseWithNamedParam
  • shouldRewriteKotlinMockitoWhenWithMultipleStatementsInUseBlock
  • shouldRewriteKotlinMockitoWhenWithClassLevelMockedStaticProperty
  • shouldNotRewriteKotlinMockitoWhenWhenStaticClassDoesNotMatchUseReceiver
• ./gradlew test (full suite) green.