[cfe] Move _create* methods inside _BuilderFactory

This avoids a lot parameter passing since the common properties are
fields of _BuilderFactory.

Change-Id: I5a4130a7f78c435ead3197f46bc6feb9e1d43851
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/436240
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>

Author: johnniwinther