Add stable unstable version (`org.matrix.msc3030.stable`) for jump to date [before `v1.6` is fully supported on a homeserver](https://github.com/matrix-org/synapse/issues/15089).
Related to https://github.com/vector-im/element-web/issues/24362 but does not solve immediately because Synapse does not supply `org.matrix.msc3030.stable` yet
Also refactored `ServerSupportUnstableFeatureController` to support multiple feature groups where any one of them will enable the setting. All features in a feature group are required. This way having either `org.matrix.msc3030` or `org.matrix.msc3030.stable` will enable the jump to date feature flag with a config of `[["org.matrix.msc3030"], ["org.matrix.msc3030.stable"]]`
Eric Eastwood