Feature/ch80914/improve error messages while importing

[jgoizueta]

See https://app.clubhouse.io/cartoteam/story/80914

This improves import error messages for connectors by extracting information from the logs in the case of generic (9999) errors.

[jgoizueta]

For all connector errors, the information returned in the import status used to be:

{ // ...
  "get_error_text": {
    "title": "Unknown",
    "what_about": "Sorry, something went wrong and we're not sure what. Try\n      uploading your file again, or <a href='mailto:support@carto.com?subject=Unknown error'>contact us</a> and we'll try to help you quickly.",
    "source": "cartodb"
  }
}

Now it is more informative:

{ // ...
  get_error_text: {
    source: "cartodb"
    title: "Connector Error"
    what_about: "Executing ODBC query to get schema↵SQL compilation error:↵syntax error line 1 at position 0 unexpected 'OOPSIE'.↵↵"
  }
}

And it appears like this in the UI:

[jgoizueta]

Dear Rubocop:

• You may not like the get_ in the get_error_text method, but it is part of our API, so I'm not going to change it, live with it.
• Using underscores as thousands separators in numeric quantities improves legibility, but my 9999 is a code, not a numeric quantity, and I like it like that.