Joffrey JAFFEUX c0179a56f8 FIX: ensures chat is present/enabled (#68) ...

Without this when chat is disabled the API is not supercharged with these methods and it will cause an exception:

```
Uncaught (in promise) TypeError: t.decorateChatMessage is not a function
    initialize discourse-math-mathjax.js:102
    initialize discourse-math-mathjax.js:119
    withPluginApi discourse-f7231bd5d10aa613b323a0cac71d8003baa74ef74f674fe4f91e4857994e661b.br.js:4735
    initialize discourse-math-mathjax.js:118
    initialize discourse-f7231bd5d10aa613b323a0cac71d8003baa74ef74f674fe4f91e4857994e661b.br.js:67
    runInstanceInitializers Ember
    each dag-map.js:192
    walk dag-map.js:121
    each dag-map.js:66
    topsort dag-map.js:72
    Ember 4
    invoke queue.ts:201
    flush queue.ts:98
    flush deferred-action-queues.ts:75
    _end index.ts:616
    _boundAutorunEnd index.ts:257
discourse-math-mathjax.js:102
```

2023-01-18 14:39:57 +01:00

..

javascripts

FIX: ensures chat is present/enabled (#68)

2023-01-18 14:39:57 +01:00

stylesheets

DEV: adds chat support (#67)

2023-01-18 12:35:27 +01:00