Better handling of invalid registration token?

### [READ] Step 1: Are you in the right place?

Looks like it.

### [REQUIRED] Step 2: Describe your environment

* Operating System version: Any
* Firebase SDK version: v6.5.0
* Firebase Product: FCM
* Python version: 3.11.9
* Pip version: Any

### [REQUIRED] Step 3: Describe the problem

This looks similar to #187, but that's been closed for years, so the similarity might no longer apply.

The crux of the issue is that not all scenarios of invalid registration IDs in FCM are supported equally. Particularly, there is the case of `InvalidArgumentError` due to an invalid registration ID which forces us to inspect the underlying `HTTPError`.

In other words, for us to handle all (known) scenarios where we should drop a particular registration ID, we currently have to:

```python
try:
messaging.send(message)
except (
messaging.SenderIdMismatchError,
messaging.UnregisteredError,
messaging.ThirdPartyAuthError,
):
# Handle errors that require dropping the registration ID
# This is reasonably ergonomic!
pass
except exceptions.InvalidArgumentError as e:
if e.http_response and "Invalid registration token" in e.http_response.text:
# Handle errors that require dropping the registration ID
# This is NOT ergonomic! Plus it relies on API internals not abstracted away by `firebase-admin-sdk`.
pass
```

Is there any chance for first-party support of this error? Perhaps by re-raising as `messaging.InvalidRegistrationIdError`?

Start at the messaging.send path and inspect how InvalidArgumentError, SenderIdMismatchError, and UnregisteredError are currently raised. Trace the HTTP response handling for the “Invalid registration token” case and determine the public error behavior needed. Done means callers can handle this invalid-token scenario without inspecting HTTP internals, with coverage for the relevant error path.

Written by the indexing model from the issue text.