Class Conflict between two Firebase modules.

### Environment
This is currently the dependencies used in my app-level Gradle build script
```kotlin
dependencies {
implementation("androidx.appcompat:appcompat:1.6.1")
implementation("com.google.android.material:material:1.10.0")
implementation("androidx.constraintlayout:constraintlayout:2.1.4")
implementation("androidx.navigation:navigation-fragment:2.7.5")
implementation("androidx.navigation:navigation-ui:2.7.5")

implementation("com.squareup.retrofit2:converter-gson:2.9.0")
coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.0.4")

implementation("com.google.firebase:firebase-admin:9.2.0")
implementation("com.google.firebase:firebase-messaging:23.4.0")
}
```

### Description
**TL;DR**: `firebase-admin` and `firebase-messaging` has the same classpath `com.google.firebase.messaging.*`, but their class's content is totally different.

Currently, I want to use both the module `firebase-admin` and `firebase-messaging` to learn about the feature Cloud Messaging, so I have installed my dependencies as above. The issue arose when I wanted to import the class `FirebaseMessaging`.

```java
// Create a list containing up to 500 registration tokens.
// These registration tokens come from the client FCM SDKs.
List registrationTokens = Arrays.asList(
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n"
);

MulticastMessage message = MulticastMessage.builder()
.putData("score", "850")
.putData("time", "2:45")
.addAllTokens(registrationTokens)
.build();
BatchResponse response = FirebaseMessaging.getInstance().sendMulticast(message);
// See the BatchResponse reference documentation
// for the contents of response.
System.out.println(response.getSuccessCount() + " messages were sent successfully");
```

While I was following [this tutorial] (https://firebase.google.com/docs/cloud-messaging/send-message#send-messages-to-multiple-devices) to build a send request to multiple devices, my IDE could not resolve the method `sendMutlicast()`

It turned out that while the imported class was `com.google.firebase.messaging.FirebaseMessaging`, the class was from the module `firebase-messaging` , which did not contain any of useful `send` method, rather than `firebase-admin`.

Is there anyway I can import the class `FirebaseMessaging` from `firebase-admin` and still keeping the two modules? I had switching the import order in Gradle file but still to no avail.

Thank you very much!

Bắt đầu với các dependency Gradle cấp ứng dụng được nêu trong issue và so sánh các artifact firebase-admin và firebase-messaging với tutorial Cloud Messaging được liên kết. Xác định xem cả hai module có thể cùng tồn tại mà không có package com.google.firebase.messaging bị trùng lặp hay không; hoàn thành có nghĩa là một cấu hình dependency được ghi lại có thể resolve FirebaseMessaging và cung cấp API sendMulticast của tutorial.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.