[IR] Rename IrAnnotationsFromPluginRegistrar to IrGeneratedDeclarationsRegistrar

In further commits, this service will be used not only for registering
  annotations, but newly generated IR declarations too

plugins/fir-plugin-prototype/src/org/jetbrains/kotlin/ir/plugin/TransformerForAddingAnnotations.kt

@@ -9,7 +9,6 @@ import org.jetbrains.kotlin.backend.common.extensions.IrPluginContext
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.IrConst
 import org.jetbrains.kotlin.ir.expressions.IrConstKind
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstructorCallImpl
@@ -109,7 +108,7 @@ class TransformerForAddingAnnotations(val context: IrPluginContext) : IrElementV
                     IrConstImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, context.irBuiltIns.stringType, IrConstKind.String, "OK")
                 )
             }
-            context.annotationsRegistrar.addMetadataVisibleAnnotationsToElement(declaration, annotationCall)
+            context.metadataDeclarationRegistrar.addMetadataVisibleAnnotationsToElement(declaration, annotationCall)
         }
     }
 }

plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializableCompanionIrGenerator.kt

@@ -93,7 +93,7 @@ class SerializableCompanionIrGenerator(
 
         val annotationCall = IrConstructorCallImpl.fromSymbolOwner(irClass.startOffset, irClass.endOffset, annotationType, annotationCtor)
 
-        compilerContext.annotationsRegistrar.addMetadataVisibleAnnotationsToElement(irClass, annotationCall)
+        compilerContext.metadataDeclarationRegistrar.addMetadataVisibleAnnotationsToElement(irClass, annotationCall)
     }
 
     private fun IrBuilderWithScope.patchSerializableClassWithMarkerAnnotation(serializer: IrClass) {