Change avscanner results priority

[PE39806]

Currently, when multiple scanners are run against a given file, we get multiple possible results and only one is shown in the preview window. The priority is defined in https://github.com/gchq/Bailo/blob/main/frontend/src/entry/model/releases/FileDownload.tsx#L43-L55. However, if a file >100MB is uploaded then ClamAV will always fail to scan the file (due to a max size limit) and this is shown as higher priority than another scanner e.g. ModelScan finding that the file is infected.

This priority should be reordered to be (highest to lowest): if file.avScan === undefined, if threatsFound(file), if file.avScan.some((scan) => scan.state === ScanState.Error), and finally default return value.