Add several files to .gitignore.

- Files created by the build script testing workflow.
- Code coverage related files.
- Zip file created by the performance testing workflow.

Author: desrosj

.gitignore

@@ -48,6 +48,11 @@ wp-tests-config.php
 /artifacts
 /setup.log
 /coverage
+/codecov
+codecov.*
+before.zip
+wordpress.zip
+wp-code-coverage-*.xml
 
 # Files and folders that get created in wp-content
 /src/wp-content/blogs.dir