[FIR] Rewrite algorithm of generating declarations by plugins

Before there was separate global stage which asks extensions
  to generate new declarations. Now it is changed to provider
  like requests, so extensions will decide do they have declarations
  with specific classId/callableId or not

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationOrigin.kt

@@ -25,4 +25,6 @@ sealed class FirDeclarationOrigin(private val displayName: String? = null, val f
     }
 }
 
-abstract class FirPluginKey
+abstract class FirPluginKey {
+    val origin: FirDeclarationOrigin = FirDeclarationOrigin.Plugin(this)
+}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirResolvePhase.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.fir.declarations
 enum class FirResolvePhase(val pluginPhase: Boolean = false, val noProcessor: Boolean = false) {
     RAW_FIR(noProcessor = true),
     ANNOTATIONS_FOR_PLUGINS(pluginPhase = true),
-    CLASS_GENERATION(pluginPhase = true),
     IMPORTS,
     SUPER_TYPES,
     SEALED_CLASS_INHERITORS,
@@ -16,7 +15,6 @@ enum class FirResolvePhase(val pluginPhase: Boolean = false, val noProcessor: Bo
     STATUS,
     ARGUMENTS_OF_ANNOTATIONS,
     CONTRACTS,
-    NEW_MEMBERS_GENERATION(pluginPhase = true),
     IMPLICIT_TYPES_BODY_RESOLVE,
     BODY_RESOLVE;