Cleanup jest config (#2959)

Some small cleanups with regards to jest
- call jest directly (nyc is integrated in jest these days)
- move jest config into seperate file so we dont clutter up the
package.json
- remove empty test file for newsletter-unit-tests
- update dependencies that touch jest
- try out v8 as coverageProvider

Co-authored-by: veeck <michael@veeck.de>

.gitignore

@@ -16,7 +16,6 @@ vendor/node_modules/**/*
 jspm_modules
 .npm
 .node_repl_history
-.nyc_output/
 
 # Visual Studio Code ignoramuses.
 .vscode/