Download page adjustment

Nobody has claimed this yet.

**Is your feature request related to a problem? Please describe.**
When deploying Remotely, for only one organization, it would be nice if you could hide the text "Note: Only the default organization's branding will apply to these." on the Downloads page at least for users who aren't logged in.

This would make the downloads page little less confusing when trying to provide support to family members or friends and this note may confuse them a little. To me it makes sense to keep the downloads page simple as possible for non logged in users, as the people we are supporting are usually not that technically savvy.

**Describe the solution you'd like**
Simple toggle setting in Server Config section of the WebUI.

**Describe alternatives you've considered**
I compile the project myself to adjust the server URLs in the binaries so I could edit it in the code, but I feel other may benefit from having this as a central toggle.

Lines I could remove manually;
https://github.com/lucent-sea/Remotely/blob/eee74139bee8da3e5d55e084b8a70e26a2d85d5a/Server/Pages/Downloads.razor#L64-L66
https://github.com/lucent-sea/Remotely/blob/eee74139bee8da3e5d55e084b8a70e26a2d85d5a/Server/Pages/Downloads.razor#L73-L75

**Additional context**

Start with Server/Pages/Downloads.razor at the referenced lines, then inspect the Server Config section of the WebUI to find where a setting could be added. Done means an administrator can toggle the setting and the branding note is hidden for unauthenticated users when disabled.

Written by the indexing model from the issue text.