chore: pass contentContainerStyle to MessageFlashList (#3385)

## 🎯 Goal

Port of [this
PR](#3348) to
the V8 release branch.

## 🛠 Implementation details

<!-- Provide a description of the implementation -->

## 🎨 UI Changes

<!-- Add relevant screenshots -->

<details>
<summary>iOS</summary>


<table>
    <thead>
        <tr>
            <td>Before</td>
            <td>After</td>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>
                <!--<img src="" /> -->
            </td>
            <td>
                <!--<img src="" /> -->
            </td>
        </tr>
    </tbody>
</table>
</details>


<details>
<summary>Android</summary>

<table>
    <thead>
        <tr>
            <td>Before</td>
            <td>After</td>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>
                <!--<img src="" /> -->
            </td>
            <td>
                <!--<img src="" /> -->
            </td>
        </tr>
    </tbody>
</table>
</details>

## 🧪 Testing

<!-- Explain how this change can be tested (or why it can't be tested)
-->

## ☑️ Checklist

- [ ] I have signed the [Stream
CLA](https://docs.google.com/forms/d/e/1FAIpQLScFKsKkAJI7mhCr7K9rEIOpqIDThrWxuvxnwUq2XkHyG154vQ/viewform)
(required)
- [ ] PR targets the `develop` branch
- [ ] Documentation is updated
- [ ] New code is tested in main example apps, including all possible
scenarios
  - [ ] SampleApp iOS and Android
  - [ ] Expo iOS and Android

Author: isekovanic

package/src/components/MessageList/MessageFlashList.tsx

@@ -1017,8 +1017,12 @@ const MessageFlashListWithContext = (props: MessageFlashListPropsWithContext) =>
   );
 
   const flatListContentContainerStyle = useMemo(
-    () => [styles.contentContainer, contentContainer],
-    [contentContainer],
+    () => [
+      styles.contentContainer,
+      contentContainer,
+      additionalFlashListProps?.contentContainerStyle,
+    ],
+    [additionalFlashListProps?.contentContainerStyle, contentContainer],
   );
 
   const currentListHeightRef = useRef<number | undefined>(undefined);