fix: isDayjs import usage for ESM (#2924)

### 🎯 Goal

_Describe why we are making this change_

recently we moved our stack to ESM (micro frontends, uses import maps).
Noticed we are getting below error in the micro-frontend that uses
`stream-chat-react`,

```
Failed to load module mfe-chat SyntaxError: The requested module 'dayjs' does not provide an export named 'isDayjs' (at index.umd-ce148d01.js:18:14)
```
on further investigation, found:

- `isDayjs` is actually not exported in `dayjs` esm build. It needs to
be accessed to through `dayjs` instance.
- We are using importmap (esm), to satisfy `dayjs` dependency, this
fails because of improper import of `isDayjs`

simply create `index.html`, with below code and run it

**this will fail,**
```html
<script type="module">
  import { isDayjs } from "https://cdn.jsdelivr.net/npm/dayjs@1.10.4/+esm";

  console.log(isDayjs);

</script>
```

**this will pass,**
```html
<script type="module">
  import Dayjs from "https://cdn.jsdelivr.net/npm/dayjs@1.10.4/+esm";

  console.log(Dayjs.isDayjs);

</script>
```

related ticket in dayjs, iamkun/dayjs#1306

### 🛠 Implementation details

_Provide a description of the implementation_

- fix import usage

### 🎨 UI Changes

_Add relevant screenshots_

Co-authored-by: Anton Arnautov <43254280+arnautov-anton@users.noreply.github.com>

Author: goldenratio

src/i18n/utils.ts

@@ -1,4 +1,4 @@
-import Dayjs, { isDayjs } from 'dayjs';
+import Dayjs from 'dayjs';
 import type { Duration as DayjsDuration } from 'dayjs/plugin/duration';
 
 import type { TFunction } from 'i18next';
@@ -100,7 +100,9 @@ export const predefinedFormatters: PredefinedFormatters = {
   durationFormatter:
     (streamI18n) =>
     (value, _, { format, withSuffix }: DurationFormatterOptions) => {
-      if (format && isDayjs(streamI18n.DateTimeParser)) {
+      // NOTE: isDayjs is not exported in "dayjs" package for ESM, hence we access
+      // `isDayjs` from Dayjs instance
+      if (format && Dayjs.isDayjs(streamI18n.DateTimeParser)) {
         return (streamI18n.DateTimeParser.duration(value) as DayjsDuration).format(
           format,
         );