Add MSC2716 to room capabilities

[MadLittleMods]

Add MSC2716 to room capabilities

Spawned from matrix-org/matrix-js-sdk#2299 (comment)

GET http://localhost:8008/_matrix/client/v3/capabilities

{
    "capabilities": {
        "m.room_versions": {
            "default": "9",
            "available": {
                "1": "stable",
                "2": "stable",
                "3": "stable",
                "4": "stable",
                "5": "stable",
                "6": "stable",
                "7": "stable",
                "8": "stable",
                "9": "stable",
                "org.matrix.msc2176": "unstable",
                "org.matrix.msc2716v3": "unstable"
            },
            "org.matrix.msc3244.room_capabilities": {
                "knock": {
                    "preferred": "7",
                    "support": [
                        "7",
                        "8",
                        "9",
                        "org.matrix.msc2716v3"
                    ]
                },
                "restricted": {
                    "preferred": "9",
                    "support": [
                        "8",
                        "9"
                    ]
                },
                "org.matrix.msc2716.historical": {
                    "preferred": "org.matrix.msc2716v3",
                    "support": [
                        "org.matrix.msc2716v3"
                    ]
                }
            }
        },
        "m.change_password": {
            "enabled": true
        },
        "m.set_displayname": {
            "enabled": true
        },
        "m.set_avatar_url": {
            "enabled": true
        },
        "m.3pid_changes": {
            "enabled": true
        }
    }
}

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• Pull request is based on the develop branch
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[richvdh]

apart from my concerns about stacking on top of MSC3244 like this, I'd like to see MSC2716 updated to document this new behaviour.

[richvdh]

I'm afraid the blocker here is about landing MSC3244 and adding the new capabilities to MSC2716, rather than the details of the code.

[MadLittleMods]

I'm afraid the blocker here is about landing MSC3244 and adding the new capabilities to MSC2716, rather than the details of the code.

Makes sense. We don't want MSC3244 to get scrapped and then have people relying on the behavior for MSC2716 to work 👍