Style new form dropdown more consistently

[jmaas-onoffice]

The current dropdown has an inconsistent style

This is the new dropdown button for adding any form:

(Sorry for the German interface. I hope the idea still comes across.)

This is how the button looks like when filtering for a specific form type:

Use a more consistent style

To make it easier to understand that the dropdown functions similarly to the other buttons, we should style it similarly:

[dai-eastgate]

@jmaas-onoffice I fixed, you can watch video and give me feedback.

https://user-images.githubusercontent.com/106214469/201288419-a2e7c9ab-5afc-4353-b8cb-680a2d201e9d.mp4

[jmaas-onoffice]

Very nice! Thank you!

By the way, I think I should have given you the design right away. I'll discuss with Linh next weekly what a good balance is for the requirements. ;)