request: usage as packge

### Is there an existing feature request for this?

- [x] I have searched the existing issues.

### Command

flutterfire

### Description

The wish behind flutterfire as package was to use it without the need to enable it globally (conflict with other projects, other flutter version)

```console
fvm dart run flutterfire
Could not find package `flutterfire` or file `flutterfire`
```

```console
fvm dart run flutterfire_cli
Could not find `bin/flutterfire_cli.dart` in package `flutterfire_cli`.
```

### Reasoning

As a dev, i want to set flutterfire_cli in my pubspec.yaml and then be able to build on iOS without any issue.

### Additional context and comments

_No response_

Start with the flutterfire command and the package's current flutterfire_cli entry point, then inspect how pubspec.yaml exposes CLI packages. Reproduce the fvm dart run flutterfire and fvm dart run flutterfire_cli commands, and consider the iOS build use case. Done means the CLI can be declared in pubspec.yaml and invoked without global installation or version conflicts.

Written by the indexing model from the issue text.