Do not track schema changes to 'raw' tables

[yruslan]

Describe the bug

Metastore tables that have 'raw' format have internal schema (currently with the only field 'path'). This can change, but it is not part of schema tracking that should be displayed to the user in notifications.

Code and/or configuration snippet that caused the issue

pramen.metastore {
  tables = [
    {
      name = "table1"
      description = "Table 1 (file based)"
      format = "raw"
      path = /some/path
    }
  ]
}

Expected behavior

The schema of 'raw' metastore tables should not be tracked.