Angular v9 schematics should print out a link to the migration
guide associated with each schematic. This way, users have an
easy way to find more information about the automatic code
transformations they will see with `ng update`.
PR Close#33258
Current we need to create and override certain compiler host methods in every schematic because schematics use a virtual fs. We this change we extract this logic to a common util.
PR Close#32827