Add an explicit error that is fired once per file for missing PDBs

[michaelcfanning]

Currently, we fire an error for each rule that requires a PDB. In some cases, a PDB may not be available (for a 3rd party binary, for example) and users may choose to explicitly assume the security risk of this condition. They should be able to manage that decision via a single issue.

The output of this error should still document all of the analysis that could not be completed because of the problem.