improve sealed workaround generation

ksp/generator/src/main/kotlin/WalkOnKSFiles.kt

@@ -0,0 +1,30 @@
+package dev.inmo.micro_ksp.generator
+
+import com.google.devtools.ksp.getAllSuperTypes
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSDeclarationContainer
+import com.google.devtools.ksp.symbol.KSFile
+
+fun KSClassDeclaration.findSubClasses(subSymbol: KSAnnotated): Sequence<KSClassDeclaration> {
+    return when (subSymbol) {
+        is KSClassDeclaration -> if (subSymbol.getAllSuperTypes().map { it.declaration }.contains(this)) {
+            sequenceOf(subSymbol)
+        } else {
+            sequenceOf()
+        }
+        else -> sequenceOf()
+    } + if (subSymbol is KSDeclarationContainer) {
+        subSymbol.declarations.flatMap {
+            findSubClasses(it)
+        }
+    } else {
+        sequenceOf()
+    }
+}
+
+fun KSClassDeclaration.findSubClasses(files: Sequence<KSAnnotated>): Sequence<KSClassDeclaration> {
+    return files.flatMap {
+        findSubClasses(it)
+    }
+}