Disable the download CSV button for zero cookies

[fellyph]

Describe the bug

In the Cookie Table view, when no cookies are listed in the table, the "Download CSV" button should not be active. Currently, the button remains enabled and clickable even when the table is empty. This behavior can mislead users into believing they can download a CSV file when no data is available.

To Reproduce
Steps to reproduce the behavior:

1. Go to the cookie table with an empty listing
2. Click on the download CSV button close to the search bar
3. Nothing will happen

Expected behavior
When the Cookie Table is empty, the "Download CSV" button should be disabled or visually indicated as unavailable to prevent user confusion.

Screenshots

Desktop (please complete the following information):

• OS: macOS
• Browser Chrome 126
• Version PSAT 0.8

Additional context
bug reported by @milindmore22