[FIR] Properly reports about conflicts in MPP setup

Checker for conflicting declarations will now check for the following
  scenarios too
- two expect declarations in different modules
- actual and non-expect declarations in different modules

^KT-63826 Fixed

compiler/testData/diagnostics/tests/multiplatform/expectActualMainInTheSameModuleDifferentFiles.fir.kt

@@ -1,6 +1,6 @@
 // MODULE: m1-common
 // FILE: common.kt
-expect fun <!EXPECT_AND_ACTUAL_IN_THE_SAME_MODULE!>main<!>()
+<!CONFLICTING_OVERLOADS!>expect fun main()<!>
 
 // FILE: common2.kt
 <!CONFLICTING_OVERLOADS!>actual fun <!ACTUAL_WITHOUT_EXPECT!>main<!>()<!> {}

compiler/testData/diagnostics/tests/multiplatform/platformRedeclarationOfExpect.fir.kt

@@ -0,0 +1,7 @@
+// MODULE: common
+// FILE: common.kt
+expect class <!PACKAGE_OR_CLASSIFIER_REDECLARATION!>Foo<!>
+
+// MODULE: main()()(common)
+// FILE: test.kt
+expect class Foo

compiler/testData/diagnostics/tests/multiplatform/platformRedeclarationOfExpect.kt

@@ -0,0 +1,7 @@
+// MODULE: common
+// FILE: common.kt
+expect class <!NO_ACTUAL_FOR_EXPECT, NO_ACTUAL_FOR_EXPECT{JVM}, PACKAGE_OR_CLASSIFIER_REDECLARATION{JVM}!>Foo<!>
+
+// MODULE: main()()(common)
+// FILE: test.kt
+expect class <!NO_ACTUAL_FOR_EXPECT, PACKAGE_OR_CLASSIFIER_REDECLARATION!>Foo<!>

compiler/testData/diagnostics/tests/multiplatform/platformRedeclarationOfExpect.ll.kt

@@ -0,0 +1,7 @@
+// MODULE: common
+// FILE: common.kt
+expect class Foo
+
+// MODULE: main()()(common)
+// FILE: test.kt
+expect class Foo