The convience observables provided by the Auth module are no longer type safe

### Version info
Angular CLI: 18.0.2
Node: 22.2.0
Package Manager: npm 10.8.0
OS: linux x64

Angular: 18.0.1
... animations, common, compiler, compiler-cli, core, fire
... forms, platform-browser, platform-browser-dynamic, router

Package Version
---------------------------------------------------------
@angular-devkit/architect 0.1800.2
@angular-devkit/build-angular 18.0.2
@angular-devkit/core 18.0.2
@angular-devkit/schematics 18.0.2
@angular/cli 18.0.2
@schematics/angular 18.0.2
rxjs 7.8.1
typescript 5.4.5
zone.js 0.14.6

### How to reproduce these conditions

**Failing test unit, Stackblitz demonstrating the problem**
n/a

**Steps to set up and reproduce**
- Create a new angular app using the latest version of the cli
`ng new angular18-firebase-test`
- Add AngularFire
`ng add @angular/fire`
- Follow the guidance [here](https://github.com/angular/angularfire/blob/master/docs/auth.md#convenience-observables) to add the convenience observables

**Sample data and security rules**
n/a

### Debug output

** Output from `firebase.database().enableLogging(true);` **
n/a

** Screenshots **

### Expected behavior
The convenience observables should be properly typed as they were in **v17.1.0**
Note in this screenshot how the IDE properly recognizes the types when using the previous release:

### Actual behavior
The observables are cast as `any` (see screenshot).

_Edit 1_
Upon further investigation, it appears the problem is related to how the `rxfire/auth` module in this file is imported. Following the import through to the definition of the module takes me to a type definition file in **v17** but instead goes to an esm module in **v18**. See related screenshot here:
Still unsure why this is happening.

_Edit 2_
Eureka! It appears in [this commit](https://github.com/angular/angular-cli/commit/f452589e2c921448b76a138a5f34ba92ad05e297) the AngularCLI now defaults to setting the `moduleResolution` compiler option in the `tsconfig.json` file to `"bundler"` by default thus causing the module to get resolved differently. Switching back to the value of `"node"` allows for the proper import of typed entities but likely causes problems with the areas targeted in that aforementioned commit.

從 docs/auth.md 中記錄的便利 observables 開始，追蹤 Auth 模組使用的 rxfire/auth 匯入。將 Angular CLI 18 的 tsconfig.json 中 moduleResolution "bundler" 下的解析結果與 v17.1.0 及連結的 Angular CLI commit 進行比較；完成的標準是 observables 在目前設定下保留其預期型別。

由索引模型根據 Issue 內容生成。