Check if filter table is found before execution starts

[Maayan-s]

When running with a filter, the filtering runs after the graph is calculated. A check to minimize 'The node is not in the digraph' exception could be added at the beginning of the execution.

Check against information schema: Pros:

• Will catch typos and miss-configuration.
• Fast and easy Cons:
• Will not catch the case where the filtered table exists in the database and schema but not in the queries (time range for example).

Search in the queries: Pros:

• Will catch typos, miss-configuration, and table not in selected queries.
  Cons:
• Might be slow.