Routes constants naming

[MisRob]

Summary

Rename RouterNames to RouteNames.

[jonboiser]

@MisRob Is it safe enough to just do a global find-and-replace of RouterNames to RouteNames?

[MisRob]

@jonboiser Yes, I think it's okay. Sometimes we use aliases like
import { RouterNames as ChannelRouterNames } from 'frontend/channelList/constants';
but it's not very often and this approach should work well for such cases too.
I am not aware of any other names that would be using "RouterNames" string that should not be replaced. Linter should catch serious problems (I don't expect any though after global find-and-replace) and we can click through the app after that.

[rtibbles]

Fixed in #2939