mip: package installation using GitLab URLs for repos in subgroups

This is more of an awareness piece and something to trigger a discussion. There is also the possibility that I am wrong and the installation process is working as intended.

I'm currently developing MicroPython [packages](https://gitlab.com/micropython-iot-projects/libraries/micropython-network-utils) on GitLab, which sit inside a 'Libraries' subgroup, which is inside a parent 'MicroPython IoT Projects' group.

Due to the way that the `mip` `_rewrite_url` function parses GitLab and  URLs, the assumption is made that the first component after splitting the URL, is the org and the second is the repository slug, which doesn't account for subgroups.

https://.com/micropython/micropython-lib/blob/96bd01ec047923c15bf936d2f77043968745542d/micropython/mip/mip/__init__.py#L63

As a result, I had to change the way I reference my packages and package extension urls and deps in the `package.json` files. My `network-utils` 'package.json' has to have the following structure:

```JSON
{
    "urls": [
        ["network_utils/__init__.py", "https://gitlab.com/micropython-iot-projects/libraries/micropython-network-utils/-/raw/HEAD/network-utils/network_utils/__init__.py"]
    ],
    "deps": [
        ["logging", "latest"],
        [":josverl/micropython-stubs/mip/typing.mpy", "main"],
        [":josverl/micropython-stubs/mip/typing_extensions.mpy", "main"]
    ],
    "version": "0.0.1"
}
```
In order to install `network-utils` with `mpremote`, I would have to use the following command:

```sh
mpremote mip install https://gitlab.com/micropython-iot-projects/libraries/micropython-network-utils/-/raw/HEAD/network-utils/package.json
```

The command below will not work, resulting in a 403 error:

```sh
mpremote mip install gitlab:micropython-iot-projects/libraries/micropython-network-utils/network-utils/package.json
```

The `network-utils-mqtt` extension  package, which requires `network-utils`, had to have its `package.json` written like so:

```JSON
{
    "urls": [
        ["network_utils/mqtt.py", "https://gitlab.com/micropython-iot-projects/libraries/micropython-network-utils/-/raw/HEAD/network-utils-mqtt/network_utils/mqtt.py"]
    ],
    "deps": [
        ["https://gitlab.com/micropython-iot-projects/libraries/micropython-network-utils/-/raw/HEAD/network-utils/",  "develop"]
    ],
    "version": "0.0.1"
}
```

The URL for the deps, which is the `network-utils` package this one extends, had to be rewritten so that the `package.json` could be found correctly.

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