Add _INFO file validation

[yruslan]

Background

Currently, most fields of an _INFO file are not validated.

Feature

Add _INFO file validation for Enceladus when Atum starts to support custom validators of _INFO files (Atum/#22 and Atum/#23)

Here is the list of validations (to be extended)

• Make sure 'Source' and 'Raw' checkpoints are present when Standardization starts.
• Country field should conform to the standardized list of countries (a MDR table).
• Source system name should be from the list of source system names (a MDR table).
• The information date should be in 'YYYY-MM-DD' format. Validate the date is the same as the report date
• Processing Start/Finish should be in a consistent format across checkpoints. Need to add validation of checkpoints created prior to Standardization.