Exclude certain tables and columns from the schema

[annieyro]

Add exceptions for columns and tables that should not be included in the schema (don't yell when schema doesn't include them).

Not sure if this is really needed - the use case for this is when one developer is updating the schema, or testing a new column addition, but testing won't be allowed since the generator wants to enforce that the generator is run and breaks the app while trying to test unrelated changes, e.g

Error converting Products record from Airtable. Could not find column of name "Original Customer Cost" in local copy of schema.js. Please run the schema generator again to get updates

The fix for now is to run the generator, but this will re-generate the schema with a column we don't want to keep since it'll be updated in a separate PR.