Notification icon is not displayed on Android 8.0

React Native version: `0.55.4`
Affected react-native-fcm versions: `14.2.1`, `16.2.3` (`16.2.4` causes build issues on Android)
Devices: Android `8.0` emulator, Android `8.0` Samsung device

Application is running in background.

The `icon` parameter is properly set on the backend as well.

Works on Android `8.1` and with other Android versions as well but not with Android `8.0`.

Related Firebase SDK issue:
- https://stackoverflow.com/questions/48495129/bug-in-notification-icon-in-firebase-sdk-11-8-0-via-firebase-console/49477930#49477930
- https://stackoverflow.com/questions/48182787/oreo-notification-bar-round-icon/49289240#49289240

Solutions and workarounds I have tried so far:
- https://stackoverflow.com/questions/52484893/unable-to-change-default-icon-for-firebase-cloud-messaging-notifications-sent-fr/52544079#52544079
I defined a default channel as described [here](https://github.com/evollu/react-native-fcm#channels) which doesn't resolves the Android 8.0 icon issue.

I also tried it by creating a notification channel as described in react-native-fcm's documentation at the same section as an option for local notifications, but it doesn't resolve the issue either unless I am missing something.

I also found similar issues like [this](https://github.com/evollu/react-native-fcm/issues/735) and I tried upgrading and downgrading the mentioned libraries as mentioned [here](https://github.com/evollu/react-native-fcm/issues/735#issuecomment-369520394), but it didn't resolve this issue unless I was adding older or newer versions the wrong way.