[FIR] Part 5. Introduce paired common checkers for expect classes

There are some cases when we want to run some platform checker not from
  platform session but from common session. All such cases appear when
  we check some `expect` class

```kotlin
// MODULE: common
expect interface A
expect class B : A

class C : A

// MODULE: platform()()(common)
actual interface A {
    fun foo()
}

actual class B : A {
    override fun foo() {}
}
```

In this example we want to report "abstract foo not implemented" on
  class `C`, but we don't want to report it on `expect class B` (as
  its supertype is always `expect A`, never `actual A`)

So to cover such cases some platform checkers were split into two parts:
- `Regular`, which is platform checkers and runs for everything except
  expect declaration
- `ForExpectClass`, which is common checkers and runs only for expect
  declarations

^KT-58881 Fixed
^KT-58881 Fixed
^KT-64187 Fixed

compiler/fir/checkers/checkers.wasm/src/org/jetbrains/kotlin/fir/analysis/wasm/checkers/WasmDeclarationCheckers.kt

@@ -5,14 +5,17 @@
 
 package org.jetbrains.kotlin.fir.analysis.wasm.checkers
 
-import org.jetbrains.kotlin.fir.analysis.checkers.declaration.*
+import org.jetbrains.kotlin.fir.analysis.checkers.declaration.DeclarationCheckers
+import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirBasicDeclarationChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirClassChecker
 import org.jetbrains.kotlin.fir.analysis.wasm.checkers.declaration.*
 import org.jetbrains.kotlin.fir.analysis.web.common.checkers.declaration.FirJsExportAnnotationChecker
 
 object WasmBaseDeclarationCheckers : DeclarationCheckers() {
     override val classCheckers: Set<FirClassChecker>
         get() = setOf(
-            FirWasmExternalInheritanceChecker,
+            FirWasmExternalInheritanceChecker.Regular,
+            FirWasmExternalInheritanceChecker.ForExpectClass,
         )
 
     override val basicDeclarationCheckers: Set<FirBasicDeclarationChecker>
@@ -39,4 +42,4 @@ object WasmWasiDeclarationCheckers : DeclarationCheckers() {
         get() = setOf(
             FirWasmWasiExternalDeclarationChecker,
         )
-}
+}

compiler/fir/checkers/checkers.wasm/src/org/jetbrains/kotlin/fir/analysis/wasm/checkers/declaration/FirWasmExternalInheritanceChecker.kt

@@ -15,11 +15,25 @@ import org.jetbrains.kotlin.fir.analysis.checkers.toClassLikeSymbol
 import org.jetbrains.kotlin.fir.analysis.diagnostics.wasm.FirWasmErrors
 import org.jetbrains.kotlin.fir.declarations.FirClass
 import org.jetbrains.kotlin.fir.declarations.utils.isEffectivelyExternal
+import org.jetbrains.kotlin.fir.declarations.utils.isExpect
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.name.StandardClassIds
 
-// TODO: extract common checker for expect interfaces
-object FirWasmExternalInheritanceChecker : FirClassChecker(MppCheckerKind.Platform) {
+sealed class FirWasmExternalInheritanceChecker(mppKind: MppCheckerKind) : FirClassChecker(mppKind) {
+    object Regular : FirWasmExternalInheritanceChecker(MppCheckerKind.Platform) {
+        override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
+            if (declaration.isExpect) return
+            super.check(declaration, context, reporter)
+        }
+    }
+
+    object ForExpectClass : FirWasmExternalInheritanceChecker(MppCheckerKind.Common) {
+        override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
+            if (!declaration.isExpect) return
+            super.check(declaration, context, reporter)
+        }
+    }
+
     override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
         val session = context.session
         val isCurrentClassExternal = declaration.symbol.isEffectivelyExternal(session)