Currently, the ViewCatalog has some duplicated code for validating views in the insert and modification paths. It also is lacking in other validation checks, including

• parsing the view pipeline
• verifying that the size of the view definition is < 16 MB

We should make a ViewValidator class that abstracts out this common code and implements these additional checks.

In addition, this validator should be in its own library in the views directory. This would allow us to move the ViewGraph cycle detection there and remove a dependency on aggregation in the core views library.