build: mirror downloads

We need to add automatic mirroring with `curl_upload_file`.

To get this moving a manual backup was done by `wget` each URL.

Each file was then uploaded with the following Fish script:

```fish
for FILEPATH in *
  switch $FILEPATH
        case *.deb
            set PARTS (string split _ $FILEPATH)
            set VERSION (string split -f 1 - $PARTS[2])
            set DST $PARTS[1]/$VERSION
        case bazelisk-*
            set PARTS (string split - $FILEPATH)
            set DST $PARTS[1]/$PARTS[2]
    end
    printf '%s -> %s: ' $FILEPATH $DST
    curl -sfLw '\n' \
      --oauth2-bearer $GITLAB_TOKEN \
     --upload-file $FILEPATH \
     https://gitlab.arm.com/api/v4/projects/418/packages/generic/$DST/$FILEPATH
end
```