fix login redirects

[nick1udwig]

Problem

Resolves #429

Solution

1. Change the login page logic to correctly determine if we are on secure subdomain. In the case where there is a non / path but we are not on a secure subdomain, this lets us redirect to the same path (including query params) after login.
2. Use @bacwyls s solution to preserve query params when logging into secure subdomain gtimoth@396a901

Testing

The cases to test are:

1. Login as normal to /
2. Login to /chess:chess:sys and see redirect after login
3. Login to /chess:chess:sys?foo=bar and see redirect after login including query param
4. Login to /chess:chess:sys and see redirect after login (secure subdomain)
5. Login to /chess:chess:sys?foo=bar and see redirect after login including query param (secure subdomain)

To test 4&5, use commit b4395e0 which has settings:settings:sys served on secure subdomain. the subsequent commit (dc93350) set it back to insecure.

Docs Update

None

Notes

There is an interesting behavior where you can login to a secure subdomain when the insecured node has not been logged in. I think this was always the case. Not sure if it is a desired behavior or not.

h/t @bacwyls