Google BigQuery improvements

[aleDsz]

We should show an output message (or a feedback message) when the user wants to upload a credentials file and it doesn't return any type of feedback about if it had an error or if it was successfully uploaded.

We should output a feedback for:

• If the file isn't a JSON filetype;
• if the file isn't a valid JSON when trying to read;
• If we couldn't read the file; and
• If the upload was a success