Improve reporting of avatar statistics

[akleshchev]

1. Add reporting of cases where viewer detects attachment count mismatch on decloud.
2. Report time/weight of attahments that arrived late. If two avatars are no longer clouded yet broken for two seconds each, the metric to transmit is 4.
3. Report 'downloading meshes' to simulator, not just 'loading attachments'
4. Exclude self from load time
5. Exclude animeshes from load time, report them separately.
6. Exclude UI avatars (ex: model upload, character edition) from reporting.

P.S. This should stay away from 2025.03. That one needs to stay comparable to release.

[kylelinden]

Server support fully released with Durian and is now ready.

[akleshchev]

This one isn't about server support. Example: existing statistics does not distinguish animeshes from avatars. We need to be able to compare decloud time on release vs 2025.03 and fixing statistics to not count animeshes would make data harder to compare.