Do not change navigation based on the scope

[klizhentas]

Navigation should not change based on the scope, because people can't find relevant sections if they are in the wrong scope. Let's fix this until we find a better solution. Example, it's impossible to know what's missing in the enterprise section if you are in the wrong scope, what hurts discoverability and creates confusion:

Vs enterprise scope:

This creates issues with google indexing as well:

We should not use:

hideInScopes feature for that reason.

Instead, our navigation should be static (similar to Gitlab) and we should use the solution I described here:

gravitational/docs#85

We should also remove the in-page scope switcher that does not work in many browsers today: (e.g. Brave does not redirect)