Query: Inline shapers for the cases when we don't need variables

Start by tracing EF Core's shaper generation and the handling of ProjectionBindingExpression for queries without collections. Confirm how repeated projections and conditional entity materialization are represented, then add coverage showing that single-use projections inline operations without unnecessary variables while preserving materialization behavior.

(queryContext, dataReader, resultContext, resultCoordinator) => 
{
    Customer namelessParameter{0};
    namelessParameter{0} = 
    {
        MaterializationContext materializationContext1;
        IEntityType entityType1;
        Customer instance1;
        InternalEntityEntry entry1;
        bool hasNullKey1;
        materializationContext1 = new MaterializationContext(
            ValueBuffer, 
            queryContext.Context
        );
        instance1 = null;
        entry1 = queryContext.TryGetEntry(
            key: Key: Customer.CustomerID PK, 
            keyValues: new object[]{ try { (object)dataReader.GetString(0) } catch (Exception) { ... }  }, 
            throwOnNullKey: True, 
            hasNullKey: hasNullKey1);
        !(hasNullKey1) ? entry1 != default(InternalEntityEntry) ? 
        {
            entityType1 = entry1.EntityType;
            return instance1 = (Customer)entry1.Entity;
        } : 
        {
            ValueBuffer shadowValueBuffer1;
            shadowValueBuffer1 = ValueBuffer;
            entityType1 = EntityType: Customer;
            instance1 = switch (entityType1)
            {
                case EntityType: Customer: 
                    {
                        return 
                        {
                            Customer instance;
                            instance = new Customer(
                                materializationContext1.Context, 
                                InfrastructureExtensions.GetService<ILazyLoader>((IInfrastructure<IServiceProvider>)materializationContext1.Context), 
                                try { dataReader.GetString(0) } catch (Exception) { ... } 
                            );
                            instance.Context = (materializationContext1.Context as NorthwindContext);
                            instance.<Address>k__BackingField = dataReader.IsDBNull(1) ? default(string) : try { dataReader.GetString(1) } catch (Exception) { ... } ;
                            instance.<City>k__BackingField = dataReader.IsDBNull(2) ? default(string) : try { dataReader.GetString(2) } catch (Exception) { ... } ;
                            instance.<CompanyName>k__BackingField = dataReader.IsDBNull(3) ? default(string) : try { dataReader.GetString(3) } catch (Exception) { ... } ;
                            instance.<ContactName>k__BackingField = dataReader.IsDBNull(4) ? default(string) : try { dataReader.GetString(4) } catch (Exception) { ... } ;
                            instance.<ContactTitle>k__BackingField = dataReader.IsDBNull(5) ? default(string) : try { dataReader.GetString(5) } catch (Exception) { ... } ;
                            instance.<Country>k__BackingField = dataReader.IsDBNull(6) ? default(string) : try { dataReader.GetString(6) } catch (Exception) { ... } ;
                            instance.<Fax>k__BackingField = dataReader.IsDBNull(7) ? default(string) : try { dataReader.GetString(7) } catch (Exception) { ... } ;
                            instance.<Phone>k__BackingField = dataReader.IsDBNull(8) ? default(string) : try { dataReader.GetString(8) } catch (Exception) { ... } ;
                            instance.<PostalCode>k__BackingField = dataReader.IsDBNull(9) ? default(string) : try { dataReader.GetString(9) } catch (Exception) { ... } ;
                            instance.<Region>k__BackingField = dataReader.IsDBNull(10) ? default(string) : try { dataReader.GetString(10) } catch (Exception) { ... } ;
                            return instance;
                        };
                    }
                default: 
                    null
            }
            ;
            entry1 = entityType1 == default(IEntityType) ? default(InternalEntityEntry) : queryContext.StartTracking(
                entityType: entityType1, 
                entity: instance1, 
                valueBuffer: shadowValueBuffer1);
            return instance1;
        } : default(void);
        return instance1;
    };
    return namelessParameter{0};
}

Currently, we generate shaper like above for a simple query like context.Customers.ToList().
Point to notice is the introduction of variables. We do this since we don't want to materialize same entity instance multiple times if it is being referenced multiple times in the projection. (this is all true only when there are no collection to be materialized, which has different structure for shaper). It also helps for a column being read from server if the column is something like binary which could have large size.

For scenarios where each ProjectionBindingExpression is being used only once and there are no collection, we can inline the operations without introducing variables.
An additional perf benefit would be that if the statement contains condition ? EntityA : EntityB then we could skip materializing one entity altogether based on how condition evaluates.