DX: validate columns in tables config

[bloep]

Is your feature request related to a problem? Please describe.
I am writing a config for over 250 database tables, each with more than 10 columns.
After I have created the config and generated a test dump (which takes 15 minutes due to the size of the database), I check it.
Columns were not changed because I had typos in the names e.g. address vs address.

Describe the solution you'd like
Before it starts exporting the data, it would be good to validate the config once against the schema to see if all columns are really there.

[guvra]

Implemented in #125 but all existing templates in app/config/templates must be tested before merging.

[guvra]

FYI, it's a breaking change, so it will be included in the 5.0.0 release.

[bloep]

Thanks for implementing it. IMHO we can close the issue