Update button groups to use not selector and remove redundant CSS.
Merge pull request #7838 from blakeembrey/btn-group-radius

Remove the overrides and resets from button groups
Fix the selectors for the .input-group-btn selector.
Merge pull request #7851 from blakeembrey/input-group-btn-radius

[v3] Fix the selectors for the .input-group-btn class
Start some nav and dropdown cleanup

* Remove border-radii on top of tab dropdown menus
* Remove the .dropdown and .dropup styles and instead place  on all
* Use  on dropdown carets intead of separately applying margin with a top alignment
* Some other misc cleanup
Restore commented out dropdown styles, get open dropdown state working again
Consolidate active dropdown toggle styles and comment out the rest
fix broke example
run make on last commit
Less specific dropdown styles, change up navbar dropdown styles
Fix navbar button docs
Fix invalid input within docs
Fix buttons within examples