[FIR] Unify implementations of toSymbol and getSymbolByLookupTag

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirAnnotationSerializer.kt

@@ -39,4 +39,4 @@ class FirAnnotationSerializer(private val session: FirSession, internal val stri
                 FirAnnotationArgumentVisitorData(this@FirAnnotationSerializer, this)
             )
         }
-}
+}

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -913,4 +913,4 @@ class FirElementSerializer private constructor(
             ProjectionKind.STAR -> throw AssertionError("Should not be here")
         }
     }
-}
+}