feat: allow augmenting event types

[myandrienko]

CLA

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• Code changes are tested

Description of the changes, What, Why and How?

Adds a new exported interface CustomEventTypes. It should be a map where keys are custom event type strings. That allows augmenting SDK's EventTypes union with more types:

import { StreamChat, type EventTypes } from "stream-chat";

declare module "stream-chat" {
  interface CustomEventTypes {
    "custom.event": true;
  }
}

type R = "custom.event" extends EventTypes ? "yes" : "no"; // --> "yes"
new StreamChat("...").channel("...").sendEvent({
  type: "custom.event", // --> allowed
});

Useful in combination with CustomEventData.

Nice next step, but out of scope for this PR, is strongly typing event data based on event type - both for internal and custom events.

[github-actions]

Size Change: 0 B

Total Size: 408 kB

ℹ️ View Unchanged

Filename	Size
dist/cjs/index.browser.js	136 kB
dist/cjs/index.node.js	137 kB
dist/esm/index.mjs	135 kB

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[isekovanic]

Thanks Matvei !

@arnautov-anton this might be relevant for you I believe and the work with OpenAPI.

Nice next step, but out of scope for this PR, is strongly typing event data based on event type - both for internal and custom events.

This is something that'll come in the next major (~October) given our OpenAPI integration. To do it now is unfortunately breaking for types. But hold on a bit longer !