py-rattler: add support for mirror middleware

[pavelzw]

Checklist

• I added a descriptive title
• I searched open requests and couldn't find a duplicate

What is the idea?

Both pixi and rattler-build allow you to specify mirrors: https://pixi.sh/latest/reference/pixi_configuration/#mirror-configuration

It would be nice if we could have this feature exposed in py-rattler as well.

Why is this needed?

We currently have a python script that installs a pixi.lock file into a custom prefix (as pixi only installs into .pixi/envs/default).
It would be nice to have this working with mirror configuration as well.

The following example currently doesn't do this but maybe adding it to AuthenticatedClient could be a way forward.

#!/usr/bin/env -S pixi exec --spec py-rattler --spec typer -- python

import asyncio
from pathlib import Path

from rattler import install as rattler_install
from rattler import LockFile, Platform
from rattler.networking.authenticated_client import AuthenticatedClient
import typer


app = typer.Typer()


async def _install(
    lock_file_path: Path,
    environment_name: str,
    platform: Platform,
    target_prefix: Path,
) -> None:
    lock_file = LockFile.from_path(lock_file_path)
    environment = lock_file.environment(environment_name)
    records = environment.conda_repodata_records_for_platform(platform)
    await rattler_install(
        records=records,
        target_prefix=target_prefix,
        client=AuthenticatedClient(),
    )


@app.command()
def install(
    lock_file_path: Path = Path("pixi.lock").absolute(),
    environment_name: str = "default",
    platform: str = str(Platform.current()),
    target_prefix: Path = Path("env").absolute(),
):
    asyncio.run(
        _install(
            lock_file_path=lock_file_path,
            environment_name=environment_name,
            platform=Platform(platform),
            target_prefix=target_prefix,
        )
    )


if __name__ == "__main__":
    app()

What should happen?

No response

Additional Context

No response