This is an implementation of the latest version of MSC4108 (version 2025). The implementation is independent of the existing experimental MSC4108 support in Synapse which is for the 2024 version.
It is configured using:
```yaml
experimental_features:
msc4108v2025_mode: <mode>
```
Where mode is one of:
- `off` (default): feature is disabled
- `authenticated`: enabled and requires an authenticated user to create a rendezvous
- `public`: enabled and
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