[FC-41030] batou_ext.file.SymlinkAndCleanup: add option "etag_suffix"

[Ma27]

Given the following deployment:

self += s3.Download(..., target=f"{version}.tar.gz")
archive = self._.target
self += SymlinkAndCleanup(target, pattern="*.tar.gz")

With this, the tarballs that are neither linked by last or current are removed. However, the .etag files from s3.Download are not.

Doing pattern="*.tar.gz*" is not an option here since this would remove ALL etag files. This means that the next deployment would download the tarball from S3 again since its etag file is missing.

This patch adds an attribute called etag_suffix that tries to delete all files matching the glob pattern pattern + etag_suffix unless pattern is equal to the file linked by current or last.

[Ma27]

Fwiw I tested this with

from batou.component import Component
from batou.lib.download import Download
from batou.lib.file import File
from batou_ext.archive import SingleUntar
from batou_ext.file import SymlinkAndCleanup


class DownloadWithEtag(Component):
    def configure(self):
        download_data = [
            ("517b30657aa12089289aa0f963fc1a6d3626e2e4d15ef81711f554f74e896f52", "069ca2a21a1be741b359053c6d6c7a9e85837ea6"),
            ("308237fba2842f5cc1c225adf6e0a32194ca8a7696cb6dd9548f9232e1b9929a", "7af6329005deda244b90a54beb1f341159a67222"),
            ("32851337df95888fcda1d1a7e12c323e5b0c547b7897ab8a40c6b947af259f88", "21f2e291762a41f55edcbb2c0789d3b741f1bad5")
        ]
        index = 2

        checksum, rev = download_data[index]
        file = f"{rev}.tar.gz"

        self += Download(
            f"https://codeload.github.com/NixOS/nix/tar.gz/{rev}",
            target=file,
            checksum=f"sha256:{checksum}"
        )
        self += File(f"{file}.etag", content="etag dummy")
        self += SymlinkAndCleanup(
            self.map(file), pattern="*.tar.gz"
        )

Didn't bother to build my own S3 bucket just for this, so I decided to generate dummy etag files.
Multiple downloads were done by changing the index variable.