[LC Call Slips] Differentiate emails when there are no results

[maxkadel]

User story

When a selector gets an email with a CSV with no results, it can be unclear whether or not that is intentional, and it also takes the selector an extra step (opening the CSV) to see that there are no results.

If there are no results matching a selector's config for a given week, they should still receive an email, but it should not attach a CSV, and the text of the email should make it clear that there were no matching results for this week.

Acceptance criteria

• When there are no lines other than the header in the CSV, it is not attached to the email
• The text of the email makes it clear that there are no results this week