[Analysis API] Cause OOB when imports change in code fragments

In K1, code fragment analysis was completely invalidated on any PSI
change. Because imports are not a part of the PSI tree of
'KtCodeFragment's, a colon tremble happened on 'addImportsFromString()'.

In K2, changes inside code fragments are always considered in-body
modifications. So, even with the colon trembling, the 'FirFile',
together with its 'FirImport's was not recreated.

^KT-65600 Fixed

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/file/structure/LLFirDeclarationModificationService.kt

@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
 import org.jetbrains.kotlin.fir.declarations.FirSimpleFunction
 import org.jetbrains.kotlin.idea.KotlinLanguage
 import org.jetbrains.kotlin.psi
+import org.jetbrains.kotlin.psi.KotlinCodeFragmentImportModificationListener
 import org.jetbrains.kotlin.psi.KtAnnotated
 import org.jetbrains.kotlin.psi.KtBlockExpression
 import org.jetbrains.kotlin.psi.KtCodeFragment
@@ -69,6 +70,11 @@ class LLFirDeclarationModificationService(val project: Project) : Disposable {
             },
             this,
         )
+
+        project.messageBus.connect(this).subscribe(
+            KtCodeFragment.IMPORT_MODIFICATION,
+            KotlinCodeFragmentImportModificationListener { codeFragment -> outOfBlockModification(codeFragment) }
+        )
     }
 
     private var inBlockModificationQueue: MutableSet<ChangeType.InBlock>? = null