Add debug logs to generateItems

It's always worth having logs for when state holders are created or destroyed (these are often the most interesting things happening in the application), so I thought it would be nice to have generateItems always log for you when it's doing that.

src/state/CallViewModel/CallViewModel.ts

@@ -715,6 +715,7 @@ export function createCallViewModel$(
       // Generate a collection of MediaItems from the list of expected (whether
       // present or missing) LiveKit participants.
       generateItems(
+        "CallViewModel userMedia$",
         function* ([
           localMatrixLivekitMember,
           matrixLivekitMembers,