Page-load with the correct homeserver selected (according to `?homeserver`).
Fix https://github.com/matrix-org/matrix-public-archive/issues/92
Also makes sure that the `?homeserver` is always available somewhere in the list; whether that be in the available homeserver list or the added homeserver list depending on it someone cleared it out or never had it because they visited from someone else's link.
Fix https://github.com/matrix-org/matrix-public-archive/issues/80
```
RethrownError: Unable to fetch rooms from room directory (homeserver=http://localhost:8008/)
searchTerm=, paginationToken=undefined, limit=9
at matrix-public-archive\server\routes\room-directory-routes.js:55:13
--- Original Error ---
Error: HTTP Error Response: 500 Internal Server Error: {"errcode":"M_UNKNOWN","error":"Internal server error"}
URL=http://localhost:8008/_matrix/client/v3/publicRooms?
at checkResponseStatus (matrix-public-archive\server\lib\fetch-endpoint.js:21:11)
at processTicksAndRejections (node:internal/process/task_queues:96:5)
at async fetchEndpoint (matrix-public-archive\server\lib\fetch-endpoint.js:38:3)
at async fetchEndpointAsJson (matrix-public-archive\server\lib\fetch-endpoint.js:63:15)
at async fetchPublicRooms (matrix-public-archive\server\lib\matrix-utils\fetch-public-rooms.js:26:26)
at async matrix-public-archive\server\tracing\trace-utilities.js:31:24
at async matrix-public-archive\server\routes\room-directory-routes.js:45:62
```