[FIR] Kmp: Deprecate header/impl keywords

Review: https://jetbrains.team/p/kt/reviews/14224/timeline

Timeline:
**(1)** Kotlin 1.1.60 https://github.com/JetBrains/kotlin/commit/59efedf610a25b004edf3d19897ce4dfca28ddb2 `header` keyword is introduced (committed on Dec 13, 2016)
**(2)** Kotlin `header`/`impl` has been deprecated (warning) at least since 1.1.60 https://github.com/JetBrains/kotlin/commit/5d251062677e09d607f295189b7978d5833e448f (committed on Sep 15, 2017)
**(3)** 1.1.60 release https://repo1.maven.org/maven2/org/jetbrains/kotlin/kotlin-compiler/1.1.60/ Nov 13, 2017

It sounds stupid but it looks like `header` was introduced and
deprecated right in the same release. Though it may be possible that we
had a release between **(1)** and **(2)** that I couldn't find

Anyway the keywords have been deprecated since basically forever

The fix is not perfect

"The perfect fix" would be:
1. Introduce a separate `DEPRECATED_MODIFIER_ERROR` diagnostic
2. Introduce LanguageVersionSettings for the `DEPRECATED_MODIFIER_ERROR`
   diagnostic

But "the perfect fix" requires:
1. Adopting `ReplaceModifierFix` in the IDE to make it work with the new
   diagnostic. `ReplaceModifierFix` is only implemented in K1 IDE. So
   there are two ways:
   1. Create a KTIJ ticket to port the diagnostic to K2 IDE (it needs to
      be ported anyway), and **mention** in the ticket that
      `DEPRECATED_MODIFIER_ERROR` also needs to be supported in K2 IDE.
      It's the ticket that nobody will probably find and fix
   2. Go and port `ReplaceModifierFix` to K2 IDE myself. It's fairly
      simple task, but I've not worked in intellij for quite a while,
      and it will take me too much time to index and compile

Considering that DEPRECATED_MODIFIER diagnostic is used only to report
`header`/`impl`, and there are literally 0 known cases when people use
it. It's just easier to convert the diagnostic to error in K2

Related tests:
- compiler/testData/diagnostics/tests/multiplatform/deprecated/header.kt

^KT-59839 Fixed

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -467,7 +467,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<KtModifierKeywordToken>("redundantModifier")
             parameter<KtModifierKeywordToken>("conflictingModifier")
         }
-        val DEPRECATED_MODIFIER by warning<PsiElement> {
+        val DEPRECATED_MODIFIER by error<PsiElement> {
             parameter<KtModifierKeywordToken>("deprecatedModifier")
             parameter<KtModifierKeywordToken>("actualModifier")
         }

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -342,7 +342,7 @@ object FirErrors {
     val INAPPLICABLE_INFIX_MODIFIER: KtDiagnosticFactory0 by error0<PsiElement>(SourceElementPositioningStrategies.INFIX_MODIFIER)
     val REPEATED_MODIFIER: KtDiagnosticFactory1<KtModifierKeywordToken> by error1<PsiElement, KtModifierKeywordToken>()
     val REDUNDANT_MODIFIER: KtDiagnosticFactory2<KtModifierKeywordToken, KtModifierKeywordToken> by warning2<PsiElement, KtModifierKeywordToken, KtModifierKeywordToken>()
-    val DEPRECATED_MODIFIER: KtDiagnosticFactory2<KtModifierKeywordToken, KtModifierKeywordToken> by warning2<PsiElement, KtModifierKeywordToken, KtModifierKeywordToken>()
+    val DEPRECATED_MODIFIER: KtDiagnosticFactory2<KtModifierKeywordToken, KtModifierKeywordToken> by error2<PsiElement, KtModifierKeywordToken, KtModifierKeywordToken>()
     val DEPRECATED_MODIFIER_PAIR: KtDiagnosticFactory2<KtModifierKeywordToken, KtModifierKeywordToken> by warning2<PsiElement, KtModifierKeywordToken, KtModifierKeywordToken>()
     val DEPRECATED_MODIFIER_FOR_TARGET: KtDiagnosticFactory2<KtModifierKeywordToken, String> by warning2<PsiElement, KtModifierKeywordToken, String>()
     val REDUNDANT_MODIFIER_FOR_TARGET: KtDiagnosticFactory2<KtModifierKeywordToken, String> by warning2<PsiElement, KtModifierKeywordToken, String>()

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt

@@ -200,6 +200,7 @@ val FIR_NON_SUPPRESSIBLE_ERROR_NAMES: Set<String> = setOf(
     "EXPOSED_TYPE_PARAMETER_BOUND",
     "INAPPLICABLE_INFIX_MODIFIER",
     "REPEATED_MODIFIER",
+    "DEPRECATED_MODIFIER",
     "INCOMPATIBLE_MODIFIERS",
     "WRONG_MODIFIER_TARGET",
     "OPERATOR_MODIFIER_REQUIRED",

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

@@ -133,7 +133,7 @@ object FirModifierChecker : FirBasicDeclarationChecker(MppCheckerKind.Common) {
             }
         }
 
-        val deprecatedModifierReplacement = deprecatedModifierMap[modifierToken]
+        val deprecatedModifierReplacement = deprecatedKmpModifierMap[modifierToken]
         if (deprecatedModifierReplacement != null) {
             reporter.reportOn(
                 modifierSource,

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt

@@ -122,7 +122,7 @@ object ModifierCheckerCore {
             trace.report(Errors.WRONG_MODIFIER_TARGET.on(node.psi, modifier, actualTargets.firstOrNull()?.description ?: "this"))
             return false
         }
-        val deprecatedModifierReplacement = deprecatedModifierMap[modifier]
+        val deprecatedModifierReplacement = deprecatedKmpModifierMap[modifier]
         val deprecatedTargets = deprecatedTargetMap[modifier] ?: emptySet()
         val redundantTargets = redundantTargetMap[modifier] ?: emptySet()
         when {

compiler/psi/src/org/jetbrains/kotlin/resolve/ModifierCheckerHelpers.kt

@@ -288,7 +288,7 @@ val deprecatedTargetMap = mapOf<KtKeywordToken, Set<KotlinTarget>>()
 
 val deprecatedParentTargetMap = mapOf<KtKeywordToken, Set<KotlinTarget>>()
 
-val deprecatedModifierMap = mapOf(
+val deprecatedKmpModifierMap = mapOf(
     HEADER_KEYWORD to EXPECT_KEYWORD,
     IMPL_KEYWORD to ACTUAL_KEYWORD
 )