Make user role mappings configurable

[dhenneke]

We want to be able to specify new role labels for power levels. This goes beyond renaming them (-> custom_translations_url or module system) and relates to matrix-org/matrix-react-sdk-module-api#6. There are different MSC proposal but nothing agreed upon, yet, so we would like to introduce a Client-global configuration until a more flexible and standardised solution will become available eventually. This assumes that all rooms in a controlled Element/Synapse installation use the same roles.

We create a new setting custom_power_level_roles (it could also be a custom_power_level_roles_url if you would prefer that):

Docs for Element Web that I will create a PR for once we agreed on how to move on

Custom user role mappings

Element maps common power levels to a human readable identifier. These are by default:

• 0: "Default" ("Restricted", if a custom default user level is configured in the room)
• 50: "Moderator"
• 100: "Admin"

They can be replaced globally with the custom_power_level_roles configuration:

{
    "custom_power_level_roles": {
        "0": {
            "en": "Noob",
            "de": "Niemand",
            // other languages...
        },
        "25": {
            "en": "Crew",
            "de": "Mannschaft"
        },
        "50": {
            "en": "Head of Staff",
            "de": "Stabschef"
        },
        "100": {
            "en": "Captain",
            "de": "Kapitän"
        }
    }
}

This will replace the complete set of default labels so you can't fall back to the default labels. Any unknown languages will fall back to the English translation.

This PR also adds UIFeature.customPowerLevel in order to hide the "Custom Level" option that might be discouraged in certain environments:

Docs for Element Web that I will create a PR for once we agreed on how to move on

• UIFeature.customPowerLevel - Whether or not a custom power level is settable.

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This is used in the following places:

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It's not used in the people list, yet, because I'm not sure what the intention there is. It looks like this explicitly uses short-forms of the labels to better fit in the sidebar so we can't just use the labels from above.

We could do:

{
  "custom_power_level_roles": {
    "0": {
      "label": {
        "en": "Noob",
        "de": "Niemand",
      },
      "short_label": { /* no label */ },
    },
    "25": {
      "label": {
        "en": "Crew",
        "de": "Mannschaft"
      },
      "short_label": { "en": "Crew" }
    },
    // ...
  }
}

but I would be happy about some feedback.

Checklist

• Tests written for new code (and old code if feasible)
• Linter and other CI checks pass
• Sign-off given on the changes (see CONTRIBUTING.md)

Type: enhancement

---

Here's what your changelog entry will look like:

✨ Features

• Make user role mappings configurable (#11441). Contributed by @dhenneke.

[t3chguy]

Needs adding to https://github.com/vector-im/element-web/blob/develop/docs/config.md

[Johennes]

I've updated the time sheeting label on this pull request. Reviewers, please take this into account when filling your sheets.

[Johennes]

Based on our chat on Matrix, I'm going to assume that overriding the translations of the existing roles will be sufficient for your needs for now and that we can avoid polluting the config / module API until the larger problem is solved on the spec level. The fixes to unbreak the latter should be landing this week (matrix-org/matrix-web-i18n#13, matrix-org/matrix-react-sdk-module-api#20, #11685 & element-hq/element-web#26262).