Fix location hash being added twice to URL

[oliverguenther]

In 0192877, a fix was made for #747, adding hashes before or after search params in the location service.

This breaks setting URLs with a single hash such as /home#footer, which is now being added twice - in the path and the search params like so home#footer?#footer

I modified an exemplary add to show this behavior: https://stackblitz.com/edit/angular-uirouter-guglw7

The link is generated in app.component.html: https://stackblitz.com/edit/angular-uirouter-guglw7?file=src%2Fapp%2Fapp.component.html

<a uiSref="home" [uiParams]="{ '#': 'footer' }" role="button">Home footer</a></li>

Click on the "Home footer" link to reproduce this error.

I added a fix to ensure the prefixed hash is only added to one of the parts. To the search path, if it exists, or to the url part if it's empty. I also extended the spec for the case of adding a hash without search.

I also added a test:watch command to test and watch tests locally which seemed to be missing (npm run watch does not exist as documented in contributing.md). Some additional format changes were made by the husky precommit it seems

[oliverguenther]

Anything I can do here @christopherthielen ?