navigating /explore by room alias does not work

[aofn]

Describe the bug
trying to open for example myserver.com/explore/#my-public-space:myserver.com will not open the desired space.
This could either be because the browser wants to jump to the css class my-federated-public-space:matrix.org
or because the api function we use behin explore is not able to use room aliases instead of id's.

Needs futher investigation.

To Reproduce
Steps to reproduce the behavior:

1. Go to an equivilant of myserver.com/explore/#my-public-space:myserver.com with a wokring room alias
2. /explore will open with the default roomId instead of the supplied alias

Expected behavior
/explore should open with the space/room my-public-space:myserver.com