Current implementation on next.carbon site

Spec

[ ] Design spec is missing finished states (both success and error)
Current implementation on next.carbon site
Shixie propose:
Some explorations on this state:

[ ] Guideline says inline loader replaces button. This feels weird to me based on below implementation. Button is too big / prominent and our inline loader type is only 12px G70.

Refs IBM/carbon-components#1749
CC @dakahn
Closing because fixes mentioned in this issue are now consolidated in issue https://github.com/IBM/carbon-components/issues/1906