Revert "Don't set a default reset provider"

This reverts commit c230d49d7c.

This reenables an edge case where an admin might want to reset, with
the default auth provider, the password of an externally-provided
user so they could "unlock" the account while it was failing. There
might be minor security implications to this, but the malicious
actor would need FS access to do it (as they would with any password
resets) so it's probably best to keep it as-is.

Removing this in the first place was due to a misunderstanding
anyways so no harm.

Emby.Server.Implementations/Library/UserManager.cs

@@ -422,6 +422,11 @@ namespace Emby.Server.Implementations.Library
                 providers = providers.Where(i => string.Equals(passwordResetProviderId, GetPasswordResetProviderId(i), StringComparison.OrdinalIgnoreCase)).ToArray();
             }
 
+            if (providers.Length == 0)
+            {
+                providers = new IPasswordResetProvider[] { _defaultPasswordResetProvider };
+            }
+
             return providers;
         }