[FIR] Make FirPlaceholderProjection having source element

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FirTreeBuilder.kt

@@ -85,6 +85,7 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val constExpression by element(Expression, expression)
     val typeProjection by element(TypeRef)
     val starProjection by element(TypeRef, typeProjection)
+    val placeholderProjection by element(TypeRef, typeProjection)
     val typeProjectionWithVariance by element(TypeRef, typeProjection)
     val argumentList by element(Expression)
     val call by sealedElement(Expression, statement) // TODO: may smth like `CallWithArguments` or `ElementWithArguments`?

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/ImplementationConfigurator.kt

@@ -453,11 +453,6 @@ object ImplementationConfigurator : AbstractFirTreeImplementationConfigurator()
             default("name", "Name.special(\"<\${diagnostic.reason}>\")")
         }
 
-        impl(typeProjection, "FirTypePlaceholderProjection") {
-            kind = Object
-            noSource()
-        }
-
         impl(breakExpression) {
             defaultTypeRefWithSource("FirImplicitNothingTypeRef")
             useTypes(implicitNothingTypeRefType)