glob negation breaks passthrough file copy

[binyamin]

Describe the bug
If one uses glob negation with passthrough file copy, nothing is copied and there is no error or warning.

To Reproduce

1. Install @11ty/eleventy via npm
2. Create file .eleventy.js, with the following contents:

   module.exports = (eleventyConfig) => {
       eleventyConfig.addPassthroughCopy("**/*!(.md)") 
   }

3. Add a .txt and a .md file, for testing purposes.
4. Run npx eleventy
5. See that the .md file is passed through.

Expected behavior
If glob negation is used with passthrough file copy, the expression should be interpreted as expected. In our example, we would expect eleventy not to copy any markdown files.

Environment:

• OS and Version: Windows 10
• Eleventy Version: v0.11.1

Additional context
Surfaced in #1483 (comment)

[Ryuno-Ki]

Would be kinda funny if the fix where similar to #693 / #677, which got fixed in #709.