TEIIDDES-1614

* TransformationValidator
 * The if-statement was modified during the 8.2 migration and lost 2 of its
   clauses, resulting in the certainty of firing. The consequence is the
   setting of the projectSymbols collection to empty when it is crucial for
   it to stay null.
 * The if-statement is only necessary for the 7.7.x resolver hence has been
   pushed down into its implementation using the postResolveCommand spi
   method

The 7.7.x and 8.3.x submodule changes have ALREADY been pushed so only this commit is necessary to pull.