Add validation rule to check for circular dependencies in view models

Designer currently allows defining transformations (view models) that depend on each other.

Need to add a validation rule (ERROR) that will detect this circular dependency.

The result is some actions like delete table/column, etc.. will end up in a StackOverflowException here: at org.teiid.designer.core.workspace.WorkspaceResourceFinderUtil.getResourcesThatUse(WorkspaceResourceFinderUtil.java:747)